looking to put in a new tranny

[outacontrl86]

i have an 86 k10 it has a 305 which will soon be replaced with a strong 350. i am in need of a tranny as i have slipping shifts leaks and the usual with a 156xxx on the clock i dont know if it was wise but i installed a shift kit about march of 07. it helped the whole summer ran great fluid was dlean as a whistle but al of a sudden i looked and it is brown. so i dont care about gas mileage it has 33's on it and will soon have 4.10's or 3.73's my real question is what can be swaped with the 700r4?