TH400 to NP205 - a tale of woe

[SilverMiner]

In 1986, attaching an NP205 to a TH400 was NOT easy. Apparently.

Does anyone remember the Turtle Expeditions? They were "overland" in the late 70's and early 80's WAY before overland was cool. I've kept most all of the 4x4 magazines I bought back in the day, and have begun supplementing the gaps from eBay. In the June 1986 edition of Four Wheeler magazine Gary Wescott of the Turtle Expedition recounted his decision to replace the tried and true SM465/NP205 combo of his 1978 K20 truck into a TH400/NP205 system. The title of the article was "The Great Exchange" and was a separate article from their travel stories.

To summarize the article, Mr. Wescott had suffered multiple problems with the throw-out bearings on the manual trans Turtle truck and decided to swap to an Art Carr TH400 with a lower first and second gear packages (2.75:1 and 1.57:1 vs 2.48 and 1.4 stock). These changes were mainly due to the success of TH400's in Class 8 and Class 4 desert racing trucks.

The problems discussed in the Four Wheeler article related mostly to the difficulty they had mating the NP205 to a TH400 auto trans. It appears they relied solely upon the expertise of Art Carr to come up with an adapter, and the Art Carr folks chose their adapter kit which transformed the 6 bolt TH400 pattern to a 4-bolt and then WELDED a 32-spline coupler to the 10 spline of their original NP205 from the manual trans. This was 100% cobbled together yet seemed to work all right except the lower gear packages ultimately failed. The focus of the article was their difficulty adapting their preferred transfer case to their desired transmission.

So, the question I have from the perspective of 2019 - why the heck didn't they go to a junkyard and pull the transfer case adapter from a 1983 or newer GM K30 system that came factory with the TH400/NP205 combo? For crying out loud, we are still mining those resources today - they must have been easier to source back then. I mean, they were in Southern California, the promised land of all parts especially when it comes to magazine articles with presumably giant budgets.

Does anyone here have any insight into why the Wescott's went to such lengths to solve what is now a minor problem requiring only money? I myself accomplished this modification fairly easily just by sending money to Advance Adapters. Thank goodness for them.

[kwmech]

Next time I see him I'll ask him. It may have been they were focused on using what they already had off of the 465?

[SilverMiner]

Originally Posted by kwmech

Next time I see him I'll ask him. It may have been they were focused on using what they already had off of the 465?

Aha, I suspect this is the most likely answer. Although the project appeared to be dripping with money at the time from my broke perspective, just waltzing into a GM dealer and ordering from the parts counter items which were in current production and readily available would NOT have been cheap. Even lavish appearing 80's magazine projects do have budgets, and the Wescott's seemed to be spending their own money.

I did get a chance to meet them once in Kalispell, Montana in the summer of 1985. They were set up in a church parking lot taking a break but were more than happy to let me ogle their truck and even peek inside the camper. Gave me some stickers, too. Wonderful folks. But then they committed the unforgivable sin of switching to a F@^& truck. Oh well, nobody is perfect.

[YoungPup1977]

I am taking your information by the years you provided,

1986 ---> attaching a 400 to a NP 205 was not easy....

1983-----> go to junkyard and get the adapter from a 1983 and newer GM

If I do the math, in the year 1986, these adapters/vehicle to be in the junkyard after 3 years of existing maybe why.... How many 2016 - 2019 vehicles do you see in the junkyards ?

[SunSoaked]

Exactly. Or at least walk to the nearest Chevrolet dealer and order the part.

[1976gmc20]

multiple problems with the throw-out bearings

Driver error ?????

[BLAZERMAN]

Like Sunsoaked said, its just a walk into any GM parts counter and thats it! Thanks to the good ole interweb its much easier sourcing hard to find parts these days...some times to easy. I wasnt even looking but tbis jumped up on my Facebook just last week...couldnt pass it up!

[kwmech]

Wow, you stole that.

[SunSoaked]

Nice score!