Does the Original Three on the Tree bolt up to a 235
You will need to use your original clutch housing with a 1954 and later 235/261.
If you have the original 6v electrical system (in particular, the 6v starter), you should use the original flywheel (and, probably, clutch assembly).
The 1954/55st 235/261 would be the most simple "drop in".
A longer GMC engine (228/248/270/302) would necessitate the most work. And, over the years, there were were different GMC engine bolt patterns for flywheels. They are very nice engines.
In all cases of a correct change to any of the Chevrolet or GMC engines mentioned above. The original 3-speed would simply be bolted to the correct clutch/housing (and clutch assembly).
