It's safe to assume his body was gotten rid of quietly.
They are shown driving off right after Mikey shoots him. They check to make sure he is dead and then drive off. His body stayed in the open.
The shooters as well were making a second attempt on a well understood rush job so it is likely that when they talked with Donny he comfirmed that it was still on and to get it done ASAP. This was what is thought to be the final conversation I would assume. The next one would have been the "it's done call". Regular conversation, yes, but not so regular they were calling daily.
Plus, one may imagine they weren't calling directly about murdering the #1-1A mobster in New Jersey. Probably pay phones since burner cells weren't around yet at that point in the show. Only explaining this because one may assume they never even "couldn't get ahold of Donny" as they died waiting to make the call that never came.
Makes sense.
