Why did we do it? RUST. The simple reason was having bought it sight unseen (I know....), we found the original 1st gen chassis was in a really bad state and was not viable to patch/repair. Everything from the body mounts to the rear spring hangers was rotten with holes and flaking rust and all the welders I took it to advised it was not salvageable. I really didn't want the truck to end up being scrapped and it was all it was fit for in its current state. I looked around all the Toyota 4Runner/Surf forums and builds and I noticed there were a few swaps being done in the US to put the 2nd gen body on the solid axle 1st gen frames - getting all the articulation benefits of the live axles under the newer shape with 4 doors. Having read a couple of write-ups it occurred to me that my solution was to do this the other way round. The only difference is that my truck was IFS so in reality there was no loss for me going to the 2nd gen IFS setup anyway, I also gained springs at the rear.The steps we followed to do the swap are actually pretty straight-forward to explain and the process only took as long as it did for us because we had to do substantial repairs to the body once it was off the frame and I decided that as it was out I would clean up and rebuild the engine. Once the repairs were done it came together really quickly. Here are the steps we followed.

Find a donor truckI sourced an early 2nd gen LN130 truck on ebay with the same 2.4 diesel engine as fitted to my first gen. I deliberately went for this because the engine and mechanicals on mine seemed fine to be re-used and I knew it would drop straight onto the mounts on the 2nd gen chassis. This would have been the perfect time to upgrade the engine, but I just wanted the truck up and running as quickly as possible because my life is complicated enough, I didn't want to miss using it over the summer months and I just didn't have the money to do it.My donor truck was really cheap as the engine had seized and it had been sat in this guys garden since 2006. The chassis was in really good condition though as was the body, which was partially parted out and also donated sheet metal for the repairs to the 1st gen body.

Break both trucks
We lifted the bodies off both trucks, removed the engines, gearboxes and fuel tanks from both, salvaged what we wanted and then cut up and disposed of the rotten 1st gen chassis. My donor 2nd gen was an auto with a seized engine. I wanted to keep the truck manual so re-used the 1st gen engine, manual gearbox and transfer case. What was critical was to swap the gear box mounts on the cross member as the auto mount is different to the manual one. Also the prop-shafts are different sizes I believe so again those were re-used from the manual 1st gen.I sourced a new poly body mount kit to replace the old cracked rubber ones and a quality 2" poly body lift kit from the Hilux Pickup Owners Club here in the UK.

Once fully repaired (Bob replaced the entire 1st gen cabin floor with the one from the 2nd gen and you wouldn't know by looking) the 1st gen body was lifted on to the 2nd gen chassis. 6 of the 8 body mounts line straight up - the front and rears are spot on and the body lines up perfectly - the ones in between the wheels need work. The one just in front of the rear tyre needs to be cut off and moved to line up and the one behind the front tyre needed some minor enlarging of the locating hole as it was about 1mm off - same both sides. That could be to do with the fact we replaced the floor though. In general though, this was relatively straight forward and the body sat square on the frame.

Fuel TankThis was a bit of an issue - we had assumed we could just reuse the 1st gen tank as they didn't look that dissimilar and that would put the filler neck in the right place against the 1st gen body, however we found that we actually had to use the 2nd gen tank as the rear of it is designed to avoid the swing arms on the rear suspension and they collided with the 1st gen one. This is where Bob did some quick and awesome fabrication merging the 1st gen filler kneck into the 2nd gen tank and plating off the orginal filler kneck. This works perfectly. I was also able to splice the sender unit wiring into the 1st gen wiring and the fuel gauge works without issue.

Other issues

We found that we had to cut the floor of the body to allow the manual shifters to come through at the right spot, but again this may be because we had recycled the auto 2nd gen floor into the 1st gen body.

The 2nd gen has the ADD vaccum based 4wd system in the front axle but I had no way to make that work so I overrode the ADD system. There are lots of posts on how to do this.Not really an issue but I spent quite a bit of time removing redundant wiring and items off the 2nd gen bits - for example as above I removed all the vaccum components for the front axle, I also removed all of the wiring for the original electric suspension settings (hard/soft) as I installed aftermarket 2" lift shocks.

Brake servo. The brake lines on the 1st and 2nd gen run a different route to the master cylinder/servo. The 2nd gen servo and master swap straight over on to the 1st gen body and is the better option as the 2nd gen has larger drum brakes at the rear so you will be using the correct components. Not sure about the front discs, I suspect these are the same size.And that's it.

The one thing I wish I had done was to transfer the dual battery wiring from the 2nd gen, but that is no biggy. For everything else I am really happy with the way it turned out given I have never done anything like this before and now it's just a case of tidying it up and slowly making improvements.

I will drop some pics and explanations below and hopefully it gives an idea of the process we went through and why.