No posi ever came in a Maverick so it has to be an open differential. I believe 70's all had a 7 1/2 inch rear. If it has a plate on the rear it is a 7 1/2 inch. If the middle section comes out the front it is an 8". Not sure if there are any other differences since it is a Mexican Maverick.
thanks for the reply the middle section does not come of i have a mustang with the 7.5 and the mavericks is different maybe a dana 44
Nothing wrong with the Dana other than putting new gears in them. They're kind of a bear to set up the way they shim them.
The later half of the 1970 US cars came with 8" rears. After finding out the 1970 Mexican cars came with 289 V8's - I'd have no idea what Ford put in them for a rear. Can you post some pictures? BTW - I moved all this into its own thread.