well I have bit the bullet as they say.I gave up trying to find axle parts for my 54 M-H..going to late model dana 44 axles with disk brakes and parts when I need them.,,what I am wondering .. will my old flatty be able to push 3.70 gearing or should I go with 4.11...who else has gone to the late axles?will the transfer box hold up or should I upgrade that too?

 

Typically it's speed (high rpm) that kills t-cases, since most all are built pretty heavy duty with moving parts that work hard at low rpm. It's the modern aluminum chain drive cases that can tolerate higher rpm.

 

kenjh..the frame width changed in 76ish and the open knuckle disc brake front axels are from 76 and up ... measure close .. measured a lotta axels before i settled on the 75 F250 HD dana 60 closed ball knuckels/drum brake i'm using ,, got the whole " kit" for 600 bucks ,.. front and rear axels np 205 transfercase ,, all 3 driveshafts they even cut the frame out of the doner truck to give me the transfercase frame crossmember..it's the correct width on the spring perches.. the backs a dead on bolt in .. just needed longer U bolts .. the front i welded side plates on the spring U bolt plate that sets on top of the spring stack as your old spring stack is narrower the the new ones are ... on gears .. i'm running a stock but fresh 239 Y @ 115 hp net ...750x16 tires ..and the new axels are 4.10s .. my orig gear was a 5.88 ..used to be about wound out at 60 mph .. and got about 6 mpg ... now she'll run down the fwy with traffic just fine ,,, but man did it cost me loaded up or pulling a grade ..grades i pulled loaded in 4th now are 3rd all the way up ...and even empty i'm dropping to 3rd in places ..4.10s are to high if you ask me.. i do get about 10 mpg now ,, but i'd give back some of that for a lower gear ..4.56s..4,88s ,, even 5.13s my 5.88s were ordered to pull a HUGE travel trailer and were just a little steep even for my taste.. but i don't know how easy to find that low a set will be in a late model axel .. i sure wouldn't go with anything higher then 4.10s ..if you are hunting transfercase as well .. go for the NP 205 as it's an all gear unit .. no chain .. and is about the toughest Tcase detroit ever made ..give the rear DS yoke a side to side pushpull as that's where miles/wear shows up 1st ..like the slop mine has ,,, oops i gotta rebuild that thing soon ,, good luck in any event ,,,