I've got a '71 220D 4 spd car. Completley love it, but 60hp and 3.92 gears doesn't work so well with modern highways...
Lo and behold I have found a '79 300D with a bad trans and body damage for cheap. Hello more power and 3.46 gears! Assuming the engine is decent, what is involved in this swap? Also, will the 220D trans hold up to the buckets of power I'll be getting from the 300 motor?
Oh, and can this be done without cutting/welding the car? It's been in the family since the 70's so don't want to do anything irreversible.

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1971 220D/4-speed ~250K mi. Family owned (dads side) through three generations since <5K miles.
1992 Chrysler LeBaron, 3.0V6 125K. Family owned (moms side) through three generations since new.
1977 Chevy Camaro Continual hotrod project
1970 Cadillac Sedan DeVille 472ci and nearly 19' long
1974 Fiat Spider Still needs work