[SCOTI]

The axles are more than likely different lengths. 1970 was the year of change from the shorter 6-lug housing to the 'new' slightly wider 5-lug housing (to better match the increased track width of the new for 71 standard disc brakes). So if it's a 70 model housing, it could be long or short depending on when it was built.

The axles will physically interchange between the housings regardless of length but the hub will possibly be .750" farther out past the backing plate. Some guys might be ok w/that & space the backing plate + brake hardware but it's not acceptable in my book. Better to just get conversion axles (typically stronger than OE axles, fresh/zero wear, direct swap w/o what-ifs).