I have a 1985 KP36. I've made a lot of mods on it mainly on the mechanical part.
1. Changed the stock 2K for a 4K motor (Brand new cylinder block)
2. Put a Weber DGV 32/36
3. Switched the T40 gearbox with a T50.
4. Put new Headers and new Radiator with a low temp racing thermostat.
All these are great. The problem I have is on the freeway. My Differential is a stock KP36 (picture attached) one with a ratio of 43:10 (4.3) so travelling long distance is a pain and hard to reach top speeds. I need to get me a 3.9 ratio differential in so I will be able to cruise at 100-130 KMH with the engine at low RPMs.
Is there a way I can only switch my Final Diff Gears without removing my entire rear axle?
Any suggestions ???