[SCOTI]

Originally Posted by bigmoe

My 65 project currently has a square body 12 bolt rear end in it (open diff). I understand they are 3/4" wider per side and at this point I'm not sure if the width is going to cause me some grief or not. My truck is a Fleetside but the box is not mounted yet in order to do any measuring. I found a guy near me who has a handful of 67-72 trucks he's parting out. I'd like to check them out to see if there's a posi worth snagging. What years are the same width as 65 and what years got wider? And when did they switch to 5 bolt wheels?

Pre 1970 is the narrower 12bolt. It will have 6-lug axles & 5-lug axles are available thru the aftermarket.

1970 was the year of 'change'. The early built 70 trucks had the narrower year. The closer things got to the 71's coming out & inventory was depleted, there was a switch to the new wider housing. It came w/longer 6-lug axles so the F/R bolt patterns matched.

71 was the first year for disc brakes in the trucks which also brought the change to the 5-lug truck pattern. It has the longer axles in the 5-lug pattern. The 73-80's shared the same length housing but in a leaf spring option only as the T/A arrangement was retired w/the body/platform changes.