trannys i have are 93 ex Z6, 91 hf, 88 dx civic, and a 91 4 speed std civic. what parts from which trannies do i use to put together a tranny that i can run at the track but also get the gas mileage out of on trips. the main shaft of the 91 hf is shot. Also i drive an 89 4dr with a d15b swap.