The bad news first--your '73 flywheel will be a 6-bolt flywheel. The better news--you shouldn't have a problem finding a flywheel--'74 140 and '75 240 are 8-bolt and any slant 4 (B21) is also the same. The good news-- rear axle ratio is the same (4.10) on 140's auto or stick except for 4 speed with OD cars which were equipped with a 4.3 ratio (even 4.56 on older 140 wagons with OD). The entire rear assembly is a bolt in from '74 and '75 160 series cars and any 240/260 series--giving you a wide range of available ratios to suit you needs. I had advised you previously that the pedals from the 240 will work based on the same revised dashboard--but maybe I was wrong on that--if that is the case you'll have to find a '73 or '74 140--or '73-'75 160 for the pedals. -- Dave