Concur with the penetrating oil solution. Many mechanics get in a rush with the oldies and start snapping bolts not realizing those parts have been together for decades. Last thing I ever want to do is thread repair as it’s a royal PITA. Patience and perseverance will pay dividends as parts for some of those vehicles are difficult if not impossible to come by.
Found Kroil a few years back that worked like a charm and saw some “new” stuff the other day that’s in a yellow bottle that I wouldn’t mind trying out. Half diesel/tranny fluid solution has been around as long as I can remember but not many younguns know about it.
Absolutely, Kroil is the best penetrating oil that I know of! It is very expensive from Amazon, but we have a local supplier that charges about half as much. It still costs so much that I use it a little bit sparingly.
https://www.amazon.com/gp/product/B0018AIJR2/ref=ox_sc_act_title_1?smid=A2UDNPGKURPVSY&psc=1