If you're working on the 68 or 69 in your pic, Dodge also used a Detroit 5380 in the 3/4 ton trucks and larger for sure, they're a little bigger than a 1410 and a pain to find. There's also a 1410 to 5380 conversion joint I've found while searching too if there's a chance that someone did some parts swapping at one point and you find two different caps.