Not sure about the part #'s but I think one of them is the regular HEI with the coil inside and the other has the smaller cap and an external coil. My 87 GP with a chevy 305 has the external coil. It was built in Canada and sold in North carolina if that matters?
I worked in the dealer at that time, and could not remember, now I do. They introduced the smaller dist, with external coil the last year of the carb.
Thanks, Ralph :texas:
There has been a lot of :beer: between then and now.