Yes, it is common in the F100s through 1976
4x4 low only?
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Junior User
Joined: Nov 2007
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From: Helena, MT
4x4 low only?
Ok all you gear heads I just picked up a strong running 74 f100 with a np435 tranny 4 speed and a dana 21 transfer case but I only have 2 wheel drive and four low is this comon in 74's if so is there a diffrent transfer case I can replace it with to get four high with out too much work on the drive lines?
Moderator & parts slinger
Joined: Feb 2007
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From: S/W Missouri, Polk county
Not to sure about your 2wd or 4 low issue, but as far as a xfer case that should work look into getting a New Process 203 (chain drive) 
, and or the better New Process 205 gear to gear drive 
,
, and or the better New Process 205 gear to gear drive ,
Cranky Old Guy
Joined: Mar 2008
Posts: 3,562
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From: Raphine, Virginia
Last two posts are correct as far difference between Dana20 and Dana21. I would think it would be a Dana20 "J" shift by 1976 but that doesn't mean much. Stuff gets swapped. Make sure hubs are unlocked and get the shifter moving. You'll find out what you have. If you have side to side movement, it's a "J" shift. I can post some pic's if you don't figure it out.
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Junior User
Joined: Nov 2007
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From: Helena, MT
no 4x4 high
ok guys thanks for the helps so far but this it what I have a DANA 21 transfer case this is on the tag on the t case on the handle of the t case it says 2 wheel forward and 4x4 back there is no 4 low or 4 high but when you put it in gear it acks like for low in just creeping and this is in second gear? so is there a diffren tcase that will give me 4 high with speeds up to 40 mph or am i stuck with a slow 4x4?
Cranky Old Guy
Joined: Mar 2008
Posts: 3,562
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From: Raphine, Virginia
In 2 or 4 wheel it is still a 1:1 ratio in fouth gear. You must have some low gears in the differentials. Normal highway speeds shouldn't be a problem. See if you can find the id tags and what size tires.
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Junior User
Joined: Nov 2007
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From: Helena, MT
4x4 low
I have 235/75 r15 on I belive this is the stock size tire. Are you talking about the tcase tags? if so am I looking for the rato? are there diffrent ratos for the same modle of dana 21?
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So if it is a Dana 21 all it has is 2hi and 4x4hi 1:1 like mentioned above. It should not act any different when placed into 4x4 as there is no low gear. Unless its biding somehow in which case I would make sure both axles are of the same gear ratio!
Cranky Old Guy
Joined: Mar 2008
Posts: 3,562
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From: Raphine, Virginia
Actually looking for the gear ratio of front and rear axle. With 4:11 gears you would be turning 2650 rpm at 55mph. 4:56 gears, 2850rpm. Second gear is still pretty low with a 3:31 ratio.
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