I just ordered a couple of 1979 Seville calipers for the GP. I have the low drag calipers now and the manual brake does not like them. The low drag calipers had a 2.75" diameter piston while the non low drag calipers have a 3" piston. The reason I ordered the Seville calipers is they only came on the 1978 and 79 which is before the low drag calipers showed up. If I ordered the 1978 or 79 Camaro calipers they could send me the 80's and up which fit but are low drag calipers and I'd have to send them back. The brand I got from Rockauto are rebuilt calipers by a US company that does their work in the US and they have good reviews. In the end the pair of calipers will be a few dollars cheaper than 1 premium chinese Napa rebuilt caliper.....