I'm sure this has been covered before. I'm looking at options at this point. I am going to change out the rear end on my 51 Effie. It was born a 6 cyl. and has the original rear end which I think is a 411. the truck now has a V8 flattie with a C4 behind it. At 50 mph the thing is really revving and it sounds like it is giving me all it can. Just wanting to make it a little more interstate friendly and wondering what housing will bolt up to the springs without doing a lot of cut and paste work.
Probably the best fit is a 9" rear end from a 1957-1972 F-100 Ford pickup. Lots of gear choices for them and the spring pads and overall witdh is the same as what you have. Depending on the length of the pinion yoke sometimes the d-shaft is even the right length.
Don't hold me to it but I think the 67-72 9" from a truck is the exact width as the original...even the spring perches are in the correct location...all you need to do is correct the pinion angle. The problem is that most trucks from that year have a pretty tall gear in them...3.70 and higher... The rear in my old 51 was from a 72....I found some used 2.75 gears from a car and put those in....very highway friendly.... Hope this helps...
Axle width is going to be your biggest problem. It is easy to cut off and re-weld new spring perches on. I used a Dana 44 out of a late 60's IH Scout in my '51 F-1. It is quite a bit narrower than the stock early Dana, but that is what wheel spacers are for, or rims with a deep offset. That rear end has worked great, came with posi and I dropped 3.08 gears in. Just had to reverse the spring pads to mount it up. Good Luck.
Explorer rears are suppose to be bolt in, if you want an axle flip. Otherwise you have to move the spring perches to the top of the axle. A lot of them have 3.73 gears with limited slip. But they did come in 3.25, 3.50 and 4.10 too, or something close to that. Late 80's to mid 90 have drum brake, after that they came with rear disc. I think they are one of the closest to the stock axle width.
I suggest finding a late 60's/early 70's F-100 rear end. It is the correct width, the correct wheel bolt pattern and it is a BOLT IN. I suggest a late 60's/early 70's with a factory automatic transmission because the gear ratio will be a LOT more favorable to highway cruising ... than most of the straight drive rear ends. Check for the TAG ... on the rear end The yellow arrow means it is a 9 inch. The " L " means Posi and the 3.50 is the ratio. W F E is the code. There are lists of the codes that tell you the original application and the gear ratio. That list is here http://www.fordification.com/tech/rearends_ford01.htm If you could find one with WDM-A ( Ford Pickup '63-'71 F-100 ) ... it would be a 3.25 and about great for your truck. A WDM-AD ( Ford Pickup '63-'72 F-100 ) would be a 3.50 gear ratio. ... also great
I agree I just put an 8.8 explorer rear end in my 51 Ford. I went with the axle above the springs, and the spring perches are about a 1/4 inch off. I made them work with a ratchet strap on the springs.