I've looked and searched the internet, but cannot find definitive answers on a couple of questions.
1. On the first page, it says factory tube OD is 3.75", but the Busted Knuckle website says 3.5" OD. Can anyone confirm if all housings were the same, and what OD is correct?
2. Is there a definitive model year when ford started putting the 1550 u-joint shafts in the factory housings? Is there an easy way to visually identify an axle that has the upgraded joints? The factory shafts will be fine for my needs (40's and drive like a bitch), so I'd like to just buy an axle with the upgraded u-joints even if I have to pay a little more up front. Looks like the 1550 Dana/Spicer shafts are about $400 or so in total +tax from Summit or ECGS.
3. Did the factory wheel backspacing on the SRW equipped trucks ever change as time went on? First page says 05-07 backspacing is 5.5" for 17" wheels. The 17" wheels I plan to use have 6-7/8" backspacing, which is OK because I will be needing to use 8x170 to 8x6.5 adapters, but I would like to stay as narrow as I can and just trying to get a feel for what I can get away with without brake clearance issues. I know there was a change in the early teens with larger rotors on the front axle, did Ford go to 20" wheels only at that point in time for increased brake to wheel clearance, or did they still offer 17" with high backspacing?
I am looking to build a passenger side drop Tundra 10.5" differential with basically all of the factory stuff from the SD front. I don't wheel hard, I just want to put in a front axle that is comparable in strength to my new rear axle (another Tundra 10.5" diff axle). I picked up a couple complete Tundra takeout axles for cheap, I got two 4.88 gearsets for $100 each, and have the ARB rear locker already. Planning on spool for the front with 35 splines to accept the OEM ford axle shafts. I am hoping to not have to do a fabricated housing up front as I do not beat my shit, but I may be forced to for axle shaft seals and also ability to put the passenger side C where it needs to go. I haven't got that far into planning. I am ready to buy an SD axle to start planning and have a lead on clean ones for $850 from a neighbor, but I want to buy one that gives me the 1550 u-joints from the factory and also has a 3.5" OD housing tube if they were indeed offered in that diameter.