Ive got a 72 with a 350 Chevy and the stock 3 speed trans and Tcase. Is there a compatible 5 Speed tranny for this setup I could put in there as I would love to have an overdrive gear?
In a 40 I wouldn't bother. A Cruiser 4 speed would be a much easier swap, a far cheaper swap, and it wouldn't make your driveline too long. If you want some overdrive, get bigger tires.
If you have a 350, then running an NV4500 with a stock chevy bellhousing would be possible. Then you need an adapter to the transfercase.
Or, you could run an H55 and split case that will need an e-brake arrangement.
Or, you could run a stock 4 speed which will much simpler in the end because of the shorter driveline and the ebrake. A stock 4 speed and bigger tires is the most cost effective thing you can do.
With enough time and money you can do anything, which means Grant's question in post #4 is the one to answer first!
The problem with taller tires it comes with a cost. Everything you gain on the top end you lose the same amount on the bottom. With the old Fairey Overdrives you gain at the top end and double your number of gears. They would hold up fine with the old F/2F not sure how they would do with a 350 and larger tires. I think a few years back there was a overdrive made in OZ but the cost was way too high.