A lot of questions, seeing as that model didn't go into production until 30 years after that model year.
Ford did build a F-750 in 1970 along with a F-700 and F-7000 (diesel). The max GVW for all three was at 22,500 lbs.
The F750 was not in production in 1990.
The F750 was not in production in 1965.
The F750 was not in production in 1993.
The Ford F750 has a higher Gross Vehicle Weight Rating, and more powerful engine options available.
According to the Ford Website, the GVWR for the Ford F750 is either 30,000 or 33,000 lbs depending on how the truck was configured. http://www.commtruck.ford.com/ctw/default.asp
one
Many websites will have Ford F750 parts. Autozone is a popular and reliable website to look for these. One other which is an option is called Partstrain.
Depends entirely on which transmission you have with it.
36 to 40 oz
The pickups won't.. the F650/F750 already use them.
Ford did not make a model known as the F750 in 1985.