transfer case

[Br 549er]

was there NP205's in 1989 one ton dually?
my searching so far has come up empty

 

[nvrenuf]

If it is a square body, yes but not a GMT 400 (both body styles were available in DRW 88-91).

 

[Br 549er]

Ok and I’m being told it was attached to a th400 as well, is that a possibility? It is or was a square 89 and the parts for sale are supposedly original… just trying to verify a few things before I pull the trigger and I appreciate your input… this is a awesome resource of info for piecing together a puzzle

 

[Br 549er]

Ok and I’m being told it was attached to a th400 as well, is that a possibility? It is or was a square 89 and the parts for sale are supposedly original… just trying to verify a few things before I pull the trigger and I appreciate your input… this is a awesome resource of info for piecing together a puzzle

If it is a square body, yes but not a GMT 400 (both body styles were available in DRW 88-91).

 

[Br 549er]

I’m new on here and definitely a learning curve on how to reply and post questions… I’ll get there

 

[waterpirate]

Welcome, and we all started the same place you are now. lol
Eric

 

[nvrenuf]

Yes, the th400 was the only auto used in the square body 1 tons until ‘90 (‘91 used a 4l80e).

Fyi, be sure to get the adapter between the trans and tcase if you’re using the th400. The crossmember only fits a 1 ton frame, it won’t work correctly on a 1/2 or 3/4 ton.

Glad I could help!

 

[Br 549er]

Yes, the th400 was the only auto used in the square body 1 tons until ‘90 (‘91 used a 4l80e).

Fyi, be sure to get the adapter between the trans and tcase if you’re using the th400. The crossmember only fits a 1 ton frame, it won’t work correctly on a 1/2 or 3/4 ton.

Glad I could help!

so if i got the crossmember that was on the one ton would that be able to be used on a 76 3/4 ton? sounds like thats available and the front driveshaft... also available is the diffs from the one ton... kind of a can of worms however i look at it regarding the diffs but they would be an upgrade... dana 60 front and dana 80 for the rear which is a dually (And not sure whats all involved in converting that to a single wheel...
lots of questions... thanks tho

 

[nvrenuf]

No, the crossmember won’t work without spacers etc. The 1 ton crossmember is almost flat whereas the 1/2 and 3/4 ton crossmembers have about 4” or so of drop designed into them.

GM didn’t use the D80 in squares so the seller is either wrong or it’s not original. The truck would have come with a narrow 63” 14 bolt if it was a cab & chassis or a wide 74” D70HD if it was a pick up (a 1/2 or 3/4 ton rear would be 68”, wheel mounting surface to wheel mounting surface).

If it’s a narrow 14 bolt you can add 2” wheel spacers and get to 67” which it close enough to probably not be noticeable. If it’s a D70HD there’s nothing you can do to narrow it except cut the housing. If it actually is a D80 you’ll just have to start measuring as it likely came from a Ford or Dodge.

Also, the DRW front axle would need the bearing hubs replaced to make it SRW.

If the price is right, the DRW front axle could be worth getting but either rear is going to take extra effort.

 

[Br 549er]

No, the crossmember won’t work without spacers etc. The 1 ton crossmember is almost flat whereas the 1/2 and 3/4 ton crossmembers have about 4” or so of drop designed into them.

GM didn’t use the D80 in squares so the seller is either wrong or it’s not original. The truck would have come with a narrow 63” 14 bolt if it was a cab & chassis or a wide 74” D70HD if it was a pick up (a 1/2 or 3/4 ton rear would be 68”, wheel mounting surface to wheel mounting surface).

If it’s a narrow 14 bolt you can add 2” wheel spacers and get to 67” which it close enough to probably not be noticeable. If it’s a D70HD there’s nothing you can do to narrow it except cut the housing. If it actually is a D80 you’ll just have to start measuring as it likely came from a Ford or Dodge.

Also, the DRW front axle would need the bearing hubs replaced to make it SRW.

If the price is right, the DRW front axle could be worth getting but either rear is going to take extra effort.

yeah, i havent looked at the parts yet but plan on it later in the week. kind of leaning on keeping my current diffs but what would you suggest changing to make driveshafts work with this swap? since the donor tcase and tranny came out of a one ton i believe they are larger than my current couplers on the 3/4 diffs...?? he also said he has the front driveshaft available so i"m assuming that might be worth picking up as well...??

i appreciate you taking the time to help
bob

 

[nvrenuf]

For square bodies, 3/4 and 1 ton rear axles use the same ujoint as well as all square body front axles use the same ujoint to both driveshafts will bolt up. Length would be your only issue.

Wait, the connection at the rear of the tcase could be an issue. The dually tcase likely has a bolt on yoke, you’ll need to identify what you currently have (if you’re using your driveshaft and not the one from the dually).

 

[bucket]

Yes, the th400 was the only auto used in the square body 1 tons until ‘90 (‘91 used a 4l80e).

Fyi, be sure to get the adapter between the trans and tcase if you’re using the th400. The crossmember only fits a 1 ton frame, it won’t work correctly on a 1/2 or 3/4 ton.

Glad I could help!

It's my understanding that the '85 and up K30's use the same crossmember as the lighter trucks, EXCEPT the K30 mounts it above the lower lip of the frame, rather than below the frame.

 

[Br 549er]

For square bodies, 3/4 and 1 ton rear axles use the same ujoint as well as all square body front axles use the same ujoint to both driveshafts will bolt up. Length would be your only issue.

Wait, the connection at the rear of the tcase could be an issue. The dually tcase likely has a bolt on yoke, you’ll need to identify what you currently have (if you’re using your driveshaft and not the one from the dually).

thanks

It's my understanding that the '85 and up K30's use the same crossmember as the lighter trucks, EXCEPT the K30 mounts it above the lower lip of the frame, rather than below the frame.

interesting and thank you

 

[nvrenuf]

It's my understanding that the '85 and up K30's use the same crossmember as the lighter trucks, EXCEPT the K30 mounts it above the lower lip of the frame, rather than below the frame.

Great info! I knew the ‘84 and older ones were different and figured GM carried on ‘85+.

 

[bucket]

Great info! I knew the ‘84 and older ones were different and figured GM carried on ‘85+.

Yeah, the '84 and earlier are definitely different. The K30 crossmember is way more "flat".