The official,unofficial guide to transfer case adapters

[1-tonmudder]

"What does this adapter fit or what adapter do I need to run transfer case X behind transmission Y" is a commonly asked question on this board and others that I frequent.This is a guide to help identify what parts you have or will need when swapping transmissions and cases.

Starting in around 1970ish until around 1977 the Th350/205 adapters used a center support bearing around the drive sleeve to hold it in place.

The sleeve had a step cut in it to accommodate the bearing,whereas the later style didn't.
Early style on the left,later on the right.



The 78ish to 80 Th350/Np205 adapters are identical to the earlier style with the exception of the sleeve and bearing.All Th350/205 will have a four bolt pattern on the trans side.


And racetrack or figure eight pattern on the case side.


During that time GM also offer the 203 fulltime case behind the TH350's and they took a different adapter.

Trans side.


Case side.


The Th400 adapters came in four different styles depending on the application.
The 400/205 adapters were either the figure eight/racetrack pattern up until about 1984,or the later round pattern used until around 91 when the body style changed on the 1-tons.

Figure 8/race tack pattern (trans side).


Case side.


The late style round pattern adapter.

Trans side.


Case side.

[1-tonmudder]

The 81ish-87 3/4 ton's with the Th400 trans used a different adapter.It is shorter/thinner than the 400/205 adapter's and has no provisions for a shifter to be bolted on the side.

Trans side.


Case side.


The 400/208 combo's used the Mil CUCV pickup's were the same as the civilian versions but use a taller or longer adapter.Otherwise they are the same as the civ version.


The 400/203's used one style and it was completely different from the others.
Trans side.

Case side.


In about 1981 GM starting usin the 208's behind the Th350's.It was only a 1-2 year deal until the 700R4's came out.The 700 and 350's both different adapters.

The Th350/208 adapter,trans side.


By 1983 they were using the 700's and it required another adapter.

Trans side.

[1-tonmudder]

The SM465 four speeds used four different adapters.The 465/Rockwell 221 adapter was the first.(I will post at a later date).

The second was the 465/205 adapter used from about 1972ish to 1980.

Trans side.


Case side.(again the racetrack/figure eight pattern)


Around 1973 until 1975 they offered the 203 behind the 465.This is the only pic I have at this time.



The 3 speed sagianw transmissions were offered with a 205 behind them as well.
Trans side.


Case side.




In 1981 they went to the NP208 and for the most part got away from the 205's except in the 1-tons.The 465 adapters changed again with the case change.

Trans side.


Case side.


Around 1986 GM went to the round pattern 205's and changed the adapters also.

Trans side.


Case side.


The late 465/205 adapter looks alot like the 465/208 adapter but the 208 adapter will work on a 205 due to it not having any provisions for a shifter(notch on the flange and threaded insert on side.



Now for the disclaimer.I am not an expert nor do I claim to be.The dates are not exact,give or take a year or two, and this is not to say that newer/older parts have been swapped in.These are merely my observations from years of swappin/buyin/sellin and usin these parts.

[jeffspower]

Good idea! I'd like to add that of the 465/ 205 combos, the later "round pattern" is IMO the best. It uses a female input like the TH400 setup. No coupler to wear, less "clink clank" on accel/ decel and far stronger. The old coupler type can can split or shear the splines off with big HP and abuse.

[1-tonmudder]

I have pulled the old 10 spline sleeve's off and the splines on the trans output have almost a razors edge on em.The later is a lot better design,just harder to come by.

[Yukon Jack]

Do you need pics of the Rockwell T221 to SM465 adapter? I'll take some good ones for you if you do. I also have a good pic with a side by side comparison of the NP205 sleeve and the Rockwell T221's sleeve.

[1969 GMC]

Here are some I have. #1 is the transmission side of the 465/221 adaptor



this is the transfer case side



the side cover



and then I had this shot saved of the 32 spline 465/205. This isn't mine, I forget where I found the pic.

[special-K]

Lookin`good for a FAQ thread for sure.How about transfer case differences for each transmission?Like spline counts and differences in shaft lengths.

[BLAZERMAN]

This has been long overdue...some great info here.

[Yukon Jack]

Here is a comparison of the measurements of the SM465/Rockwell T221 combo and the SM465/NP205 combo (the NP205 is a 70's vintage with a yoke style rear output.)





And here are some pics of the coupler/sleeve differences. Both couplers are for mating to the SM465.







The first pic makes the one coupler's diameter look alot bigger, but it is actually just a bit bigger.

And a note, the 3 speed manual/Rockwell coupler is longer than the SM465/Rockwell coupler and can be cut down to be used if you were to swap from the 3 speed manual to the SM465 but still staying with the Rockwell transfer case.

[1-tonmudder]

Do you need pics of the Rockwell T221 to SM465 adapter? I'll take some good ones for you if you do

I spent about 3 hours taking,gathering,and posting pics yesterday and thought I had em on my comp but I didnt.By the time I realized I didnt it was four degrees outside and I wasnt goin back out.

Thanks for the pics.

Lookin`good for a FAQ thread for sure.How about transfer case differences for each transmission?Like spline counts and differences in shaft lengths.

I'm hoping to start on my doubler this coming week and will try to get some pics and work on it.

Does anybody have any pics of the TH350/Dana adapter ???? The one used before the 205's.That is the only adapter I have never had one of.

[xbanone]

Excellent information. This will be very helpful in my saginaw to sm465 conversion. Thank-you 1-tonmudder!

[1-tonmudder]

I got my late style 465/205 adapter today so I added that info.

[402Bowtie]

Old thread--does anyone know where this information (with pictures) can be found today?