1971 monaco differential swap

Folks,

I've got a 1971 dodge monaco with an open differential with (what i believe is a 2.71). I'd like to swap it out for a complete 3.23 suregrip or 3.55. I'd like to still maintain highway speeds of 80 with no problem as I will be towing stuff, so maybe the 3.55 is a bit too high. Where can I go about finding a replacement...remanufacturers? And what part number do I look for? If I remember correctly there were two different types in 1971 and I need to look on the pumpkin to find out?

Thanks in advance...
David

You'll be towing stuff at 80 mph?

Dr Diff or Randy's Ring and Pinion are big sellers of 8 3/4" centersections. Be seated before you look at the prices for a complete rebuilt unit with SG, though!

ok cool...do I have a 741 case or a 742?

Thanks!

If yours is original it's a -489.

Any of the 3 will interchange, though. -741 has the smallest pinion stem dia and is the weakest (but it's not necessarily weak, that always starts a lively debate! ) and therefore the cheapest.

Don't get too hung up on which version you get IMHO. I ran the original -741 in my 68 Fury for several years after putting a 440 in.

oh ok, so they are all interchangeable w/o have to swap out the axle?

oh yah ok. doh. they are interchangeable. thanks

yes they all inter change with stock axles

IMO.3.55 is the best all around gear for street duty and towing with a car

3.23 are a little better for gas milage

2.?? are for highway cruz and no towing for mpgs

3.91s are great out the hole,but 3500rpms at 60mph and no mpgs over 70mph

results will vary with gear and weight with highway speeds and towing

what engine and tranny combo???thats gotta be figured in as well as tire size for rpm/mph/mpg results

80 mph should not be a problem with any gear,the weight,distance,rpm,mph,mpgs,milage traveled will though