[80SPORT]

Both use vacuum modulators

TH400 uses electric kickdown;you will need the switch(mounted under dash) and wiring from a th400 truck;th350 used cable

TH400 used a different yoke and in the truck app uses a 2 pc driveshaft;many trucks came with TH400 ...even small blocks w tlr pkg so your best bet is to find/buy a parts truck as you will need the extra crossmember to hang the steady brg on;if you have a car app th400 that uses a slip yoke rather than the truck app bolt on yoke you could use your original driveshaft but you would need to modify length to fit