Pete and I were talking about these extensions as I have seen a few in the wreckers on trucks. I think Pete they might have been a GM over the counter part. GM 999282 The ebay post says for 79-88 trucks and 82-88 camaro.
I had an aftermarket chrome extension but it was made of much too heavy material. I didnt use it as I was afraid it would probably damage the valve cover. I ended up using the valve cover and fill pipe and also the dipstick and tube from an 85 Chevy van. This was on a 350 installed in a 59 Chevy one ton. It made it much easier to check and add oil. Mind you this was a long time ago, I sold the truck in 2008.
Ironically , had this new in a package hanging in the wall for who knows how long ? did this engine build and swap last week, seemed like a good spot for it . I punched an extra hole , then peened it in place .
