GQ1-standard ratio?????

[zieg85]

OK, just wondering if anyone has verified what the above RPO code translates to or if anyone has that code and has verified what ratio it is???  I looked at a 1980 C20 that lists that on the sticker in the glove box.  Before I go back there to test drive it I'd sure like to know what it is if possible...  5.7L/SM465 combo if it matters...  Just a plain truck, no AC, just warning lamps instead of gauges.  What impressed me was that the body is real clean for a work truck.  The drawback for me is it has a utility box on back...

[Stewart G Griffin]

GQ-1 std ratio is either 2.56 or 2.73 depending on the year.   We would have to double check for 80, but it's either 2.56 or 2.73---it's in either the brouchures or the tech pages in the tech section.   For example, for 83 it was 2.56.   You can refer to my neurotic thread entitled "AXLE CODES" for more info.

http://forum.73-87chevytrucks.com/smforum/index.php/topic,3785.msg17374.html#msg17374

[Stewart G Griffin]

P.S.   i just re-read the post and it's a c-20 in question so now GQ-1 may not mean 2.56/2.73.  Give me a few mins.

[Stewart G Griffin]

Ok, scratch all that stuff concerning 2.56 and 2.73;  That applies to 1/2 tons ONLY.


Do you know what the GVWR rating is for the truck?    If it's up to 8500, GQ-1 for a 3/4 ton with the 350 and 4spd is 3.21.  But this also depends on what tires it has.   If it's above 8500 lbs, then GQ-1 is 3.42 with the 350/4spd combo.

So, you've got quite a bit of power either way.

It's all in the heritage pages:
http://www.gmheritagecenter.com/gm-heritage-archive/vehicle-information-kits.html

[zieg85]

I'll check it out.  I will copy the vin down and decode it for the braking.  I need to pop off a hubcap to see if it is a SF or FF 14 bolt.  It lists the G80.  The higher gear the better...  FWIW the tire size listed on the RPO code is 9.50x16.5 so I bet it is lower GVW.

[Stewart G Griffin]

For some reason GQ-1 would be 3.42 if you have the smaller 7.5 x16 tires if the GVWR is 8500 or below  (?)


You can only get 9.5x16.5 if the GVWR is 8500 and higher.   This is looking better and better.   This is all very confusing and i'm sure "we'll" figure it all out eventually.

[Stewart G Griffin]

i just want to say that i think every truck 3/4 ton or higher is a medium duty truck in my opinion.    Of course most states do not agree.....

[zieg85]

Thanks Stewart I'll report back if I buy it or pass on it.

[zieg85]

I drove it today, feels much like the 3.21 that is in my 85C20.  It is a 7100 GVW according to the weight sticker but it has a full floater in back...  Didn't know they made C20 cab and chassis's but that is how the VIN sort of decoded.  Vin doesn't make sense to me CCL23AS18xxxx.  The A is supposed to be a number which indicates the year which should be a zero (0).

http://www.chuckschevytruckpages.com/7980VIN.html  clears up the VIN question...