I have a 1976 Model 70 push feed that I need to replace the barrel on. It is a LA in 243. I have seen some take off barrels which look like the push feed type, IE no extractor cut. They are marked Model 70 SA (Short Action?) Will they fit the standard LA receiver?

I believe some barrels were 16tpi, and others 28tpi.

Yep that is what has me worried. The barrel is on an auction site. You buy what you see. I do not know what my barrel has for TPI. Don't know what the other possible ones have. I do know that the later barrels with the extractor cut will not fit without work.

The 28 TPI barrels are off the newer FN made model 70's. You should be good to go on the 16 tpi ones; headspace considered however.