transfer case interchange - The 1947 - Present Chevrolet & GMC Truck Message Board Network

lurch115 · 06-05-2010, 01:04 AM

i am currently working on a project that started with a 1977 K5 blazer drivetrain under it and have swapped out the axles already. what i am wondering is if a t-case from a 1984 1/2 ton with a 700r4 tranny will mate up to the 1977 turbo 350 tranny that i have splining and all? the 1977 is currently a full-time chain drive and i would like to go to the part-time aluminum gear drive.

bikes&bowties · 06-05-2010, 03:17 AM

off the top of my head I couldnt say for sure if the spline is right and I am pretty sure you'd need a different adapter..

For an idea.. why not put a 205 on... a few dollars more and it would be WAY heavier duty to go with the axles...

84 400 · 06-05-2010, 03:45 AM

The splines on the Trans output are 27 which i believe is the same between a th350 and a 700r4. The 700r4 uses a longer transmission output shaft. The 700r4 would be mated to a np208. the 208 is also a chain drive unit. It is lighter and uses a lower low range which is nice for offroad. But it is still weaker because it is chain drive and aluminum. I swapped in a np205 which is gear drive and cast iron with a th350 adapter and 27 spline input.

lurch115 · 06-06-2010, 01:09 AM

bikes&bowties....i know the 205 would be ideal, and am planning to go that route eventually....the reason i was asking is cause i have the aluminum t-case sitting in my garage.

84 400... so the 208 should mate up to a th350 just fine then?

the reason i am asking is cause i don't wanna drop the heavy cast iron turd only to find out i am gonna have to put it back in.

USSkoval · 06-06-2010, 02:34 PM

No, the th350 output shaft is not long enough.

sierra4x4 · 06-06-2010, 04:08 PM

The TH350 has 2 different 4x4 shaft lengths.
One is used for the 203 and 205 cases and the other is longer and is for the 208 tcase.

MrBeast · 06-06-2010, 04:10 PM

save yourself the trouble and get a 205. the 208 is very very very very weak. if it breaks out where you are offroad and you have to hire a wrecker to get you home, it will have been cheaper to get a 205. I bought one this morning with a TH350 attached for 300 bucks. They are around, you just have to look.

lurch115 · 06-15-2010, 12:03 AM

thanks for all the info. i am planning to sit under it here soon and check to make sure the linkage isn't out of adjustment also.

06-05-2010, 01:04 AM	#1
lurch115 Registered User Join Date: Oct 2006 Location: iowa Posts: 722	transfer case interchange i am currently working on a project that started with a 1977 K5 blazer drivetrain under it and have swapped out the axles already. what i am wondering is if a t-case from a 1984 1/2 ton with a 700r4 tranny will mate up to the 1977 turbo 350 tranny that i have splining and all? the 1977 is currently a full-time chain drive and i would like to go to the part-time aluminum gear drive. __________________ "Horsepower is how fast you hit the wall, torque is how far you carry the wall with you." '84 chevy half ton short box 2wd, 67,000 actual miles '03 chevy 1500 HD crew cab 4x4 standard box, 6.0L

06-05-2010, 03:17 AM	#2
bikes&bowties Registered User Join Date: May 2009 Location: Washington Posts: 663	Re: transfer case interchange off the top of my head I couldnt say for sure if the spline is right and I am pretty sure you'd need a different adapter.. For an idea.. why not put a 205 on... a few dollars more and it would be WAY heavier duty to go with the axles...

06-05-2010, 03:45 AM	#3
84 400 Sb 400 club Join Date: Nov 2005 Location: NH / MA Posts: 2,741	Re: transfer case interchange The splines on the Trans output are 27 which i believe is the same between a th350 and a 700r4. The 700r4 uses a longer transmission output shaft. The 700r4 would be mated to a np208. the 208 is also a chain drive unit. It is lighter and uses a lower low range which is nice for offroad. But it is still weaker because it is chain drive and aluminum. I swapped in a np205 which is gear drive and cast iron with a th350 adapter and 27 spline input. __________________ 1984 chevy c10, built 400sb,.(SOLD) 77 K10 Project / daily driver "The Grinch" http://67-72chevytrucks.com/vboard/s...d.php?t=318363 1956 Willys Wagon (327 chevy) Project (Now Buick 225) 1980 Corvette L-48 4 speed 1992 Mustang GT built 5.0 5 speed 1985 C10 LWB Sold 1982 K10 SWB plow truck Parted out 1986 D30 M1028 fire brush truck Parted out

06-06-2010, 01:09 AM	#4
lurch115 Registered User Join Date: Oct 2006 Location: iowa Posts: 722	Re: transfer case interchange bikes&bowties....i know the 205 would be ideal, and am planning to go that route eventually....the reason i was asking is cause i have the aluminum t-case sitting in my garage. 84 400... so the 208 should mate up to a th350 just fine then? the reason i am asking is cause i don't wanna drop the heavy cast iron turd only to find out i am gonna have to put it back in. __________________ "Horsepower is how fast you hit the wall, torque is how far you carry the wall with you." '84 chevy half ton short box 2wd, 67,000 actual miles '03 chevy 1500 HD crew cab 4x4 standard box, 6.0L Last edited by lurch115; 06-06-2010 at 01:10 AM.

06-06-2010, 02:34 PM	#5
USSkoval Registered User Join Date: Jul 2009 Location: West Jefferson, OH Posts: 999	Re: transfer case interchange No, the th350 output shaft is not long enough. __________________ -Andy '77 K5 Blazer '78 K10 Shortbed '78 C20 Suburban '79 K30 Crew Cab Dually '84 C10 Short Stepside '88 K20 Suburban

06-06-2010, 04:08 PM	#6
sierra4x4 Registered User Join Date: Jan 2009 Location: Canada Posts: 308	Re: transfer case interchange The TH350 has 2 different 4x4 shaft lengths. One is used for the 203 and 205 cases and the other is longer and is for the 208 tcase.

06-06-2010, 04:10 PM	#7
MrBeast high-Tech Red Neck Join Date: Feb 2008 Location: Livingston, MT/On my boat WA/BC/AK Posts: 2,294	Re: transfer case interchange save yourself the trouble and get a 205. the 208 is very very very very weak. if it breaks out where you are offroad and you have to hire a wrecker to get you home, it will have been cheaper to get a 205. I bought one this morning with a TH350 attached for 300 bucks. They are around, you just have to look. __________________ "He used to be a pretty nice feller, now he's a welder!"

06-15-2010, 12:03 AM	#8
lurch115 Registered User Join Date: Oct 2006 Location: iowa Posts: 722	Re: transfer case interchange thanks for all the info. i am planning to sit under it here soon and check to make sure the linkage isn't out of adjustment also. __________________ "Horsepower is how fast you hit the wall, torque is how far you carry the wall with you." '84 chevy half ton short box 2wd, 67,000 actual miles '03 chevy 1500 HD crew cab 4x4 standard box, 6.0L



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