But that wouldn't have required a bicycle trailer, surely, unless the transactions were all in coins.
Whatever they were stealing was heavy enough that it needed multiple bicycle trailers to transport. I assume back to their own garages.
The only things I can think of would have been catalytic convertors, but that doesn't make that much sense because there is only 3-7 g of platinum-group metals in one and you have to have a significant technology strip them. Not something that the 5 guys would be able to do on their own. The salvage place has the contacts to buy the metals, not the guys stealing it, surely.
And word would certainly be getting around town and back to Joe Kennedy that someone else was edging in on his CC sales.