Possible 1978 Gmc Cheyenne 10 Donor (VIN: tkt248f723093)

[nica89yj]

Good Evening,

As all of the previous modifications ever done to my 89 YJ (4.2) this one has to go through Jeepz.com ok. Today I found a possible Transmission/transfer case/differential/leaf springs/Drive shaft donor. I’ve been wheeling 33x12.50 super swampers for over 3 years and want to go a little bigger, How does the 1978 Cheyenne 10 sound? Originally the pick up had the 292 I6 shooting 120 hp which now has been removed. It has a Manual 4 speed transmission (i think) and everything seems to be in fair condition. A 350 V8 could also be swapped in but I’m thinking of keeping the 258 since it still runs strong. Price on the parts is good and I really would love to get rid of my d35/d30 and run 8bolts.

Thanks for reading.

 

[FLynes]

If the truck you're looking at has 8 bolts, then it's going to be a 3/4 ton, not 1/2 ton. It would lead me to believe that someone swapped those in there, so you'll have to do some investigating, to find out where they came from.

GM 4x4 1/2 ton models had 6 bolts. I've owned a few 70's GM trucks. There are a few anomalies out there; my '72 Big Block 402 Suburban was a C-10; it had all 3/4 ton suspension but still retained the 5 bolt pattern...it was officially called the "Heavy Half".

 

[jps4jeep]

All assuming the truck is an original condition and equip truck.

the 258 is not worth it.

if it is a 4 speed, it's a sm 465, it is a good wheeling transmission, if you use your jeep to drive on the high way, there is no overdrive so your milage will suffer.

The T-case is most likely a np 208, and it is worthless. the low ratio in it is like 1.92-1 your 231 stock is I think 2.72-1

Regardless of the lug pattern, your front axle is going to be a D44. if you have a K30 (Cheyenne 30) SRW, then it would be a D60 (IDed with King pins), but as far as I know, a K30 was never Badged as a Cheyenne 10. the rear axle could be a number of things, if it is 6 lug, either 10 or 12 bolt, if it is a 8 lug, could be a SF14 bolt, FF14 bolt, or a Eaton 072

the stock springs are nothing special, they are probably 52" springs, 3" wide. you would have to remove a number of leafs to get hte spring rate comprabile to a jeep spring

If it had 5 lug axles, you got a 2wd truck


Personally I would pass unless it was free, then I would snag the transmission only.

 

[nica89yj]

So basically the transmission is the only part worth swapping? If axles are both 8 bolts (will post pics) aren’t those a significant strength gain over the d30d35 combo? Will not keep the 258, and will continue to shop around for a V8.

 

[xjmarc]

Also keep in mind that the Chevy front axles were passenger drop so you would have to use the Chevy t-case and if you keep the 258 you have to reroute the exhaust to clear the front driveshaft. Also Chevy fronts are low pinion so you add a bit of angle to the driveshaft.

 

[nica89yj]

Ur right about the exhaust, But now iam getting second thoughts of how much of an upgrade the switch would be. The same guy is selling a 350 v8 of a 73 suburban that i could mate with the 4 speed transmission of the cheyenne (3/4 ton) transfer, and diffs. Seems like alot of work...

 

[RangerRick]

Be aware that Chevrolet switched to it's "corporate" 10 bolt front axle somewhere in 77 so a 78 would most likely be a corporate 10 bolt and if it had 3/4 ton payload capability or swapped in axles it would only have the 8 lug hubs on a corporate 10 bolt. To get a Dana 44 open knuckle with any real guarantee from a 1/2 or 3/4 ton Chevy, it needs to be a 1973-1976 with no swapped parts. 1 tons would have the D60 in it, this is only regarding the half & 3/4 tons.

I did lots of research before selecting the donor truck for my CJ-7 front axle.

Rick

 

[jps4jeep]

IIRC, 78 was the last year for the 44 front, 79 was the first year for the 10 bolt front. 76-77 was the first year for the D60 in the K30's depending on the build date.


you do not need a Chevy t-case, a dana 300 fron a CJ can be easily mated.



EDIT.. My mistake, 77 was the last year for the 44 front.