Hmm, I though all the 70s GM covers had the welded tab, just in different places depending on the size of the balancer.
There were at least two designs (3 spoke and circle with diag cut).
I would have assumed a 72 L48 is the same as 69 Camaro L48s and used the same timing cover (3 spoke with 8" balancer welded tab). Aslo used on Z/28s so they are getting pricey.
