Will a 400 transmission fit on 305 Chevy caprice engine?

Answer 1

You didn't mention the year of the caprice so I'll try to cover a couple scenarios that will depend on whether it originally had a turbo 350, a metric 200, or a 700R4.

First, understand that Turbo 400 Transmissions were made with 2 possible bell housing bolt patterns: One for Chevy engines, the other known as a BOP case which stands for "Buick/Olds/Pontiac and also bolts to older Cadillac engines.

A turbo 400 is also longer and has a larger diameter drive shaft yoke with more splines.

So to answer your question, a Chevy turbo 400 case will bolt to a 305 Chevy engine (a BOP case won't), but to use a turbo 400 transmission in a car that has a 305 engine and most likely had a turbo 350 or 700R4 transmission originally you would have to change or relocate the crossmember, change the driveshaft yoke and have the driveshaft shortened. The shift linkage is in the same location -- the only difference being if it had a 700R4 the shift indicator would read L2 for low gear and OD for Drive if you put a 3 speed non overdrive transmission in place of a 700R4. The vacuum modulator is on the passenger side front of a 400 instead of the back for a turbo 350 so you'd have to run a new vacuum line, or in the case of a metric 200 or 700R4 which has no vacuum modulator you'd have to run a vacuum line. Also, if it originally had a metric 200 or 700R4 with a lockup torque converter you'll lose that with a turbo 400 and the check engine light will stay on as turbo 400's don't have lockup torque converters -- at least I've never seen one and don't believe they ever made a lockup 400, if they did it's rare. Turbo 400's also use an electronic downshift solenoid with a switch mounted to either the throttle linkage or under the dash near the gas pedal (to downshift for passing gear). Technically a swap like this is possible, but it's much easier (and probably cheaper) to replace the transmission with the same kind you removed, or rebuild the one you have.