Not sure on either subject. For seat covers, you can check around the 'net. There are some companies that are starting to get into repro parts for the A/G body cars (Year One, G Body Parts, etc.). If there isn't what you're looking for, then you could check around at local trim shops. Some places can get matching material, and make up or repair seat covers. As far as the numbers go, that could be tough. I don't know of any way of checking numbers on Olds vehicles in the States. If it was a Pontiac, you could check with Pontiac Historical Services, but that's for Pontiac only. Likewise, here in Canada, if the car was originally sold here, then you could check with Vintage Vehicle Services with GM of Canada. In the U.S.A., I'm not sure of any source for Olds info. Once again, you could check on the internet. There are a couple of Olds sites that might be able to help you. Also, check for Olds clubs, both locally and nationally. Shouldn'y be too hard to Google for clubs, and possibly someone can help you out that way. I know that Olds had a 260 V8/5 speed option in '78, but I wasn't aware of the 305/4 speed being available in the Olds. I thought that driveline combination was only available in the Chevrolets. Good luck with your search.