I agree this sounds more like the timeing chain has sliped . I am not sure what carb was used on your model. but on my 37 with a 216 it has a Carter W1 on it
------------------- 37 Chevy 1/2 Ton
37 Chevy 1/2 Ton 86 Chevy Blazer 98 Drudge 24 valve Cummins One worn out Timberjack