There was a ebay seller called HEIDIZZY that was making drop in GM HEI distributors machined out of billet specifically for the GMC V6. HE seemed to drop out of eBay several years ago. There is another seller on ebay that builds GM HEI's with a smaller cap, not a retrofit as all the internals are GM HEI, I forgot his name, maybe someone else may know. As far as building a modified unit from a 231 V6 it's not that hard and all the info is on Jolly's 6066gmcguy.com site. I built the HEI for the 305 my pickup back in 1991 and now the same distributor resides in the 478M V6 in my truck today.
