i think that the point i want to go to an FS5W71C is when i would go KA/SR/FJ, which right now all i want to do is drive the crap out of it and get every MPG that i can squeeze out of it, ill worry about performance later if i get board of my 500hp FJ20 S12 :D(still being built... slowly lol.) Wonder what I'd have to do to get it to the "MPG" version status, the one that got 56mpg back in the day...
I don't know how long the transmission are, but i could possibly find a 71C out of an S12(came in the SEv6 and some l4 models) which I know is shorter than the one in the 240sx, which also makes me think that they might fit, id just have to find a b310 bell housing(which means i should probably stick to finding an entire trans instead)
the FJ trans is a 71B trans, same thing out of a 280ZX, DR30 Skyline and the MKI S12s. heres a pic from someone with a Btrans, maybe that might provide more info
so what your saying is that the automatic motor/trans share the same bolt pattern and the 5speed/trans motor share a different pattern? thats teh gayz...
also, i haven't found anything on the "A10 510", apparently production was 67-73 or something like that