Let's play "guess the gear ratio"

[mountainexplorer]

From the factory, what would you most likely think the axle gear ratio would be in a:

1986 Chevy 1-ton 4x4 Crew Cab SRW with a 6.2 Diesel, TH400 and NP205.

My guess would be 4.10.
4.56 would be too low for a Diesel. But did they put 3.73's in them also?

 

[readymix]

I'll guess 4.10:1

Or more likely 3.73:1

 

[MTBLAZER89]

3.73's

 

[84_Chevy_K10]

3.73s

 

[mountainexplorer]

Thats what the guy who own it thinks too. I had an '83 factory 6.2 1-ton that had 4.10s, but wasn't sure if they had many 3.73 60 fronts in the diesels as well. Makes sense though. He says the truck gets 19mpg too.

 

[diesel4me]

I havent checked my diesel's gear ratio's yet--I'm guessing it has 3.73's,because it seems higher geared than my 74 K20 with 4.10's and the same size tires--the diesel trucks probably are more likely to have a higher ratio(like 3.42 or 3.73 vs 4.10 or 4.56's)due to the lower rpm torque of the diesel--but any ratio can probably be special ordered I suppose.....Someday I'll pull the cover and change the lube,and "de-code" it..

 

[blazd88]

iv got one for you!
1979 1 ton dana60/14ff. it has a 292 straight six,sm465,205tc
it was a telephone line companys truck so it has a utility bed with a large hydrolic arm in the bed.
WHATS THE RATIO?

 

[atho]

iv got one for you!
1979 1 ton dana60/14ff. it has a 292 straight six,sm465,205tc
it was a telephone line companys truck so it has a utility bed with a large hydrolic arm in the bed.
WHATS THE RATIO?

4.56

 

[mountainexplorer]

I'd also guess 4.56 as the ratio from the factory on that 6 cylinder 1-ton.

 

[diesel4me]

Hmm---phone company truck huh?? ---I've seen some 80's vintage 1/2 ton 2wd phone CO.trucks with 2.56 rear axle gears and a wimpy 5 speed like a chevy monza used in the 70's--so in a one ton 4x4 its a wild guess,but I'm going to say its probably a higher ratio more than a low one,maybe 4.10's or even 3.73's if they had them available in a one ton--seems the phone companies around here thought high axle ratio's would give better fuel mileage--I bet they were wrong!!..

Or maybe someone with a brain had the truck equipped with a nice low gear like 5.13's or even 6.17's--I've seen electric company bucket trucks with 4wd and dana axles set up for off road use--my friends brother drives a similar rig with an auger for installing telephone poles,his had a 366 with a 5 speed,but it was a 60 series truck,with REAL low gears--topped out at 55mph when the govenor kicked in......

 

[tarussell]

Between myself and a few buddies we have purchased several K-20 and K-30 trucks with 292's in them and so far all of them have been 4.56 geared trucks .
the trucks were as follows:
1978 K-20 292 465/205 Dana 44 / 14FF open 4.56's
1978 K-30 Cab Chassis 292 465/205 Dana 60/14FF open 4.56's
1979 K-30 Crew Cab 292 TH400/203 Dana 60/14FF open 4.56's

As for the original topic my vote is 4.10's !
The early N/A 6.2's were not real hot performers and needed a little help in the gear department and as for my expirience 4.10 is very common in the 1 Ton applications - that being said it could have been ordered with 3.73 / 4.10 or 4.56's .
Tom

 

[westtexask5]

is there any way that it could be a real low ratio like 2.56 or so?

 

[84_Chevy_K10]

is there any way that it could be a real low ratio like 2.56 or so?

Nope, D60s don't go that high. That's why the D61 exists, and GM never used it AFAIK.

 

[mountainexplorer]

Got another one for everyone:

1979 Chevy K10 1/2 ton 4x4, 292 6-Cylinder, 4spd/205, 12 bolt rear, 10 bolt front.

 

[atho]

Got another one for everyone:

1979 Chevy K10 1/2 ton 4x4, 292 6-Cylinder, 4spd/205, 12 bolt rear, 10 bolt front.

Hmm..3.73

 

[mtn. burb]

4.56:1


All the military K30's had'em.

 

[Zeus33rd]

For the original question, my guess is for 3.42's or 3.73.

1979 Chevy K10 1/2 ton 4x4, 292 6-Cylinder, 4spd/205, 12 bolt rear, 10 bolt front.

For that, I say 3.73's. Was there ever a factory 4.10 12b?

 

[tarussell]

As for the 1979 half ton truck I would guess a 4.10 gear .

Tom

 

[mountainexplorer]

I was given a '76 rolling frame once that looked like it had a 4spd and 203 combo originally... wasn't sure on the motor, but it was a 1/2 ton and had 4.10 gears in a 12 bolt and Dana 44.

The '79 I got was a factory 6-cylinder 1/2 ton 4x4 truck. When I got it, someone had already swapped a 14 bolt under the rear, but the front was still a 6-lug 10-bolt. I still havent actually pulled covers, but I was assuming 4.10s on that one.

 

[Tuff84blaze]

MountainExplorer I have a question for you thats kind of related to this topic, where would you recomend somebody from the Spokane area go to have a set of front and rear gears installed on a 10 bolt front 14 sf rear, and about how much should I expect to pay?

Thanks.