Re: Block question
With minor differences, all three and four cylinder blocks from the time they were Chrysler until Merc discontinued the Force line were the same. So, if your question is: will one mount in place of the other, the answer is yes. In fact, the three and four cylinder blocks used the same mounting stud pattern and are also interchangeable with each other.
Only thing you need to be careful about is the splines in the crankshaft. Sometime in the mid to late 1990s, Merc changed them and I am not sure if the jet models were different also. Ask the seller to count the splines and compare the count to your engine.
Up until at least 1990, the crankshafts and mating drive shafts had 15 splines. If I remember correctly, the Merc units had less.
