I have a 69 with a 4bbl 350 horse, hideaways, power windows, but otherwise very plain Jane. It’s quite low geared I don’t have a tach, but the fastest I can comfortably cruise at is about 70mph and it’s revving pretty high three grand plus. Would you guess it has a 3.55 or 3.90 rear? Just looking for an opinion. I will have to get it up on a lift in the spring to look for codes. Thanks. Dean Kamloops BC. ps that’s my then 10 year old boy diggin it.