I am replacing a straight six 250 with a 350 V8, But for the time being I am going to stay with the original manual 3 speed tranny, my question is that I will be replacing the clutch and the part numbers for the 250 clutch and 350 clutch are different. First of all what is the difference and which one should I purchase? Any help would be appreciated. Thanks Paul

Get a clutch package for a V8, 10.5 inches diameter would be good. Buy new parts, not rebuilt, at least IMO. Transfer the clutch ball from the 6-cyl block to the V8 block for supporting the Z-shaft. You will have to shorten the throttle linkage from firewall-to-carb, if using the six cyl linkage, otherwise, buy a V8 linkage.