There’s a debate whether they are anything different from 340-4 valve covers. I personally think they are unique based on the survivor cars I’ve seen. I can’t recall all the subtle differences (two or three, I think) but the most obvious difference is the height of the spark plug wire tab on the D/S cover. IMO, the AAR/TA cover tab was about a 1/2” taller than the 340-4 version. Some chalk up any differences in the valve covers to supplier variations rather than intentional AAR/TA design. The taller tab makes sense to me when you look at how the brake booster vent hose attaches to the manifold on a 340-6.