Odd lack of 6 cylinders in 1975???

[82355]

I was checking out Vehicle Information Kits, because I'm a nerd. I found something strange while checking for transfer case availability. In 1975, GM did not offer a 6 cylinder in any K series trucks, except for K20's. K10 pickups were only available with 8 cylinders. Blazers, and Suburbans were only available with V8's.

In fact, the only year you could get a 6 cylinder in a K10 Suburban was 1973. It was available with the 250.

The 1975 K20 pickups were available with a 292. It could be paired with a TH350, which was the only way to get an automatic with a TH350 in 1975.

Martin

 

[82355]

Also, for some reason, in 1975 you could only get a C20 Suburban with a 454. No small block available.

Martin

 

[dyeager535]

I'd be willing to bet it was all emissions related. I can't recall how much effect CAFE had at that time, but I know emissions was getting worse, and they probably just decided to get fewer drivetrains certified that year.

Also might be tied into what customer trends showed, judging by what is around today the 6 cylinders never did sell as well as the 8's so perhaps that would explain why the 6 was neglected that year...if the sales and/or modifications necessary to meet the standards didn't justify the expense that year, that would make sense too.

I'm not THAT old school, but even up until fairly recently wasn't it pretty common for people to buy 2WD trucks for towing? That would make sense to me then why the C20 Suburban got the 454 exclusively.

 

[82355]

Yeah, I assumed it was something to do with emissions. 1975 would have been the first year for catalytic converters, not?

The odd thing was it was just that one year. In 1976 the 6 cylinder was back in 4x4 models.

GM also dropped the two year experiment of all V8 equipped trucks having a full time transfer case. I wonder why? If people didn't like manual transmission with full time 4x4, or if it was to increase fuel economy ratings?

Martin

 

[dyeager535]

It would be interesting to hear the "inside story" on a lot of this stuff. It's all rather boring now I suppose, but to hear what drove them to do certain things would nonetheless explain much.

I seem to recall 1975 being first year for converters. With the hodge podge of converters in trucks, who knows what a 6 would have gotten that year, especially when you start factoring in GVW.

To be honest, not sure why they even used the 203 in the first place. I guess so forty years later people would have a source for doubler parts? Seriously, those cases are massive. It seems like the 203 drivetrains last just as well as any of the part time drivetrains, so it doesn't seem like it would have been dropped due to failures.

 

[diesel4me]

My '75 Blazer had a factory 250 six & 3 speed manual transmission (A rare Tremec!),but despite it being labeled a "K5" on the fender badges,it was a 2WD version...the engine was the first version of the integral head design with a one barrel carb...


There may have been exceptions for fleet vehicles,because I have seen some Suburbans between 1973-75 or so,that had 292 straight sizes in them with either TH400's or SM465's in the fleet at the gas & electric plant my dad worked for,but they were probably 2wd too,I cant recall if any of them were 4WD...pretty sure they were C20 2wd ones..

I think the NP-203 got dumped due to the poor fuel mileage not being emissions friendly and excess wear on drivetrain parts,and being a heavy ingot ,more than it not being a "good" transfer case...they were plenty stout if you ask me..but the chain drive probably didn't impress owners of the older trucks with NP-205's either...around '75 or so is when GM decided to "downsize" everything in hopes of increasing fuel economy and reducing emissions...

 

[82355]

Yeah, they kept the 6 cylinders in 2wd's. It was only 4x4's that didn't get the 250 in 1975.

Martin