Most the stuff is made by the same manufacturers so quality in most cases won't vary much. There are several companies making things like disk conversion kits so its worth looking to choose the one that best suits your needs.
I've been happiest with the service I've received from LMC. Prices may be higher but I'll pay a little more to be treated with a little courtesy and my experience with some of the others with cheaper prices will assure I'll never go back to them. Amd LMC's catalogs are great with all the illustrations. Much better than most the others.
I almost always buy something from Jim Carter when I see him at a swap meet. Chevs of the 40's is the vendor closest to me, though they are too far away for a casual trip to pick something up, if I'm going to be in that area and need something I will plan a stop.
I find as a hot rodder much of what I need doesn't come from an old truck vendor. I regularly buy from Rock Auto and actually they often have old truck parts that the old truck guys don't.
Another thing to consider is shipping time. I became very frustrated with a vendor who would allow me to online order at the end of the day Sunday but would never ship till Tuesday. The result was I never received my order until after the following weekend. I was willing to pay for expedited service or fast shipping but the vendor never made it work so if I needed something to continue a project I lost a weekend.
Part of that problem was just their distance from me. But I won't buy from them anymore because they clearly communicated that I was the problem not them.
