I was asked a question in pm that makes more sense for me to reply to here than just to one guy/gal. So here goes.....
I was looking at your pics on your frame restorations. How do you go about doing it. I take it you blast the frames first? Do you make up all your own repair parts? I just got a 65 and want to redo the frame and eventually the whole truck
First let me say, it depends what you start with. Like most Patrols the frame is going to be nasty, neglected and have 40-50+yrs of funk on them. There is always the odd chance though that the truck was taken care of or came from the desert and if that is the case you could skip a thing or two on it. For me, a frame restoration is something I only want to do on a truck once, ever. So I am going to do it right and to the best of my ability. If you do this, the frame will be ready to survive another 50 or so yrs of use and abuse. On top of this, if you really want a sealed up frame it takes considerable effort because of how the frames were made. Not only are they fully boxed they also have a ton of seams and seams = rust. Can you imagine going through the effort of restoring a frame and then a year or two later it is bleeding rust out of these seams!?
First, a good pressure wash. If it is a clean frame a cold water will do it. If not you may need to scrub it with Simple Green and repeat the wash and keep doing it until it is clean. However, the fastest and best method is a hot water pressurer washer. These are much hotter than you will find at the car wash, most go to 300+*, some are adjustable. The big brand and most common and best made are the Hotsy. You can rent these and take home to do up your truck. It is well worth the rental and diesel fuel it runs on expense, trust me on that. In addition to the wash I also wash out the inside of the frame as best I can. I raise the back end of the truck, they don't drain well out the back, only the front. I then use an attachment I made for the garden hose that fits inside the small holes in the frame rails. I push it in there and wash until I have nothing but clean water coming out of the frame.
Once washed, it is time to sand blast. Now if you skip washing and go straight to blasting you will not make any friends at the sand blast shop or if doing it yourself you will find out why they won't like you. Grease, oil, grime are bad news when blasting, a sand blaster really doesn't want to take this stuff off, it will but not easily. A commercial outfit re-uses their sand (I do too, it is expensive and I hate waste) and when you bring them nasty greasy or oily items it pollutes their sand. They hate it, trust me on that and that is why I wash first. My local sand blast shop charges about $250 to do a Patrol frame, not bad really. You can go at it with a grinder (flap discs), a sander and wire wheels on various tools. In is a major pain in the butt though, takes tons of work and will never get the frame as clean as sand blasting. Not to mention it is dangerous and not fun at all with the wire brush, steel thorns are not joke and hurt plus hard to get out of your clothes! After blasting it takes some effort to get all the sand out of the frame, the more effort you put in the more sand you will get out. I start by putting the frame up on end, ya know lean it up against the shop or house or whatever, front of the frame down. Then I get on a ladder and smack the frame rails with a rubber mallet. After this I use compressed air. I use attachments I made for the compressor and also the shop vac to get inside the frame rails via the small holes.
Now you can spray right on the sand blasted steel and most people do that. Make sure you clean it thoroughly first, sand dust will be present even if you can't see it. A wipe down with MEK is recommended, only use MEK for wipe downs, anything else can cause you problems. I take things a step farther so I don't paint right after blasting. I believe Nissan dipped the frames because there is paint applied to the inside of the frame and dipping is the only way to do that. Since dipping is very expensive, I do it myself.
At this point I will do any frame repairs that are needed. I always and I mean always cut apart the #2 cross member, this being the one below the trans. Even if it looks good from the outside, I promise you it has funk inside it. I cut off the top and work with it from there. I always remove the "H" shaped reinforcement brackets inside the cross member, they are always corroded and often falling apart from rust. In my opinion it is a poor design because the H brackets trap dirt, mud and funk. So I re-enforce the cross member with 1/4" plate. I weld this in to the bottom of the cross member. I have also fully fabricated a new #2 cross member when they are to far gone to fix up, I have made them out of 3/8" plate. The stock cross member is stamped out though and takes considerable effort to make new and make it look stamped. Front frame rail horns are often damaged and need repairs, for these I usually cut 1/4" patch pieces and weld them in rather than trying to straighten up twisted old pieces. Very common for previous owners to have drilled holes here too and it is simply easier to make new pieces than mess with trying to fix trashed horns. The firewall body mount outriggers are also often trashed on Patrols. These get hung up off road or bounced off rocks, logs or whatever. Very common to find these bent up as well as the caps on the bottom of them twisted and trashed. For these I make patch pieces out of 1/4" plate and I always make new caps for the bottom. Make sure and use
cold rolled for this vs hot rolled. CR won't distort like HR and is a finer grade of steel. HR is considered cheaper steel in the industry for use when distortion won't matter.
I paint the inside of the frame with RustBullet, it is similar to POR15 but easier to use. Basically I am talking about a rust encapsulating paint. After doing this three times I found it helps to thin down the RB. Before applying the RB I do an acid bath. I use Metal Blast, a RustBullet designed product for use before their paint. The acid etches, cleans and preps the steel for paint. You simply put it on, I use a spray bottle, let it sit and then wash it off with water, by wash I mean wipe down not spray with water. It turns rust black. To get the RB inside the frame is a real nasty job but it does work and it works well. I use a honey bottle or a turkey baster and squirt the RB into the frame holes. I then make a brush I can get inside the frame rails via the small holes. It is simply a coat hanger cut up with a rag attached to the end of it. I work it hard and as best I can inside the frame. I also flip the frame as I am doing this and keep one end of the frame lower than the other. My buddy who did this on his 68 GTO calls it back flooding or just flooding the frame with paint and that is what I am doing. Once I feel it is coated right, I leave the frame higher on one end and let the excess drain out. What is really important is getting the seams that make up the c-channels flooded with paint. There is rust between these seams you will never get out unless you cut the frame apart so sealing the seams with the rust encapsulating paint is key to me. I also coat all seams on the outside of the frame, I even hit up welds. I do this to encapsulate the rust that is there. After it drys, about 48hrs I start sanding. The RB makes a mess and will be all over the outside of the frame, if you top coat on this you will have ugly marks everywhere the RB is located. So I smooth and blend the RB down in order for the top coat to look good. This can take a lot of work depending on how messy the RB was or if you did all the seams on the outside of the frame. A final note about RB, it will fill pitting if you have pits on the frame from rust. You then sand it back and the RB stays in the pits giving you a nice clean smooth surface where the pits are gone.
Once this is done and I am happy with it I move on to primer. I use a high quality 2K Epoxy primer I get at the automotive paint supply shop. You can get it in colors, I use black because it makes any areas you may miss with top coat harder to see or notice. I will lay down 2-3 coats of the epoxy, I may or may not sand between coats. Once I am happy with the primer I move on to the top coat.
For top coat I have used DuPont Imron and also on this truck Bill Hirsch chassis black. The Imron is super nasty stuff and I like how the Bill Hirsch went down and looks. Semi-gloss is what you want on the frame to look stock. High gloss looks bad in my opinion and flat black doesn't do it for me unless on one of my off-road trucks. Top coats are generally applied at 30min to 1hr intervals, how many coats you apply is up to you, I go 2-3.
So there you go, that is how I do it. Many other ways to do it out there, such as dipping, galvanizing or powder coating. I don't like powder coating because it will chip and touching it up just doesn't work. I like to be able to touch up the frame/chassis over time. Both the Bill Hirsch and the Imron match up very closely to a Duplicolor semi-gloss black in a spray can. It is also easy to touch up using a small brush with the BH or Imron.
Last bit,
do not spray paints unless you have the right gear. I know painters that don't even get this. A canister mask is not going to cut it in terms of vapors and other nasty stuff in automotive paints. You must use a fresh air system, anything less and you are seriously risking your health. It costs money to restore a frame right, on the materials and time but also on the tools. If you don't have the right tools and are not willing to buy them, don't do it. Nervous system damage is no joke, there is a reason they put so many warning labels on these paints, they are super nasty. I repeat, only paint with a fresh air system, I have a Hobby Air full face mask, it only cost me about $500 and was worth every penny I spent on it.
Cheers
The frame is really starting to look outstanding though, hard work pays off. 
One thing I love about these trucks is the frame, it is so stout and overbuilt. The engineering that went into it is also impressive not to mention 50 some odd years ago some Japanese guy stood around all day with a stick welder building these, back in the day before robotics in car manufacturing. To me that makes them super cool. 
I got it all sanded back though, I am coating the outside with Rust Bullet and then will top coat that with chassis black. 
