RPO codes

[Paintmycar2]

Ok so I know the rpo/option codes on the inside of the glovebox. The question comes when there are handwritten rpo codes on the upper part of the firewall that match what drivetrain is in the truck (1971 C10). RPO says its a 350 with a 400 behind it and the writing says ls9 and m38, and off to the left I am guessing is the order number? Just had me curious and I figured I would ask yall. Oh and long time reader first time posting.

Thanks,
Joey

[Bigdav160]

LS9 is a 4 barrel truck 350 and M38 was the RPO code for an automatic transmission.

I thought a 1971 C10 would have had a TH350(?)

edit, I guess you're asking about the other numbers? order number would my guess too

[IronCanine]

Solid first post.

Pics of the firewall and SPID would be helpful if you are suggesting that there is a discrepancy between the what the firewall says and what the SPID says. It sounds like you know, but JIC here is a list of the RPO codes for reference: http://outintheshop.com/options.html

I would generally expect that M38 would be a TH350 and what you'd expect in a 1/2T truck. But my limited understanding is they may have played a little fast and loose with the auto RPO codes. M49 is listed for both TH350 and TH400 with specifics called out in the SPID.

The passenger side of the firewall is usually reserved for the model number of the truck. For instance CE10934 would be a 2wd V8 1/2T LWB fleet side.

Here some links to threads about factory markings:

http://67-72chevytrucks.com/vboard/s...d.php?t=591402
http://67-72chevytrucks.com/vboard/s...d.php?t=431775
http://67-72chevytrucks.com/vboard/s...d.php?t=694023
http://67-72chevytrucks.com/vboard/s...d.php?t=674971

[Paintmycar2]

Soon as I get a chance to get some pictures put up somewhere to link to the passenger side is marked ce10904, whichbmakes sense as model number which matches spid and drivers side has the ls9/m38 even though the glovebox tag matches vin and other equipment it lists trans as m49edit though I've read the m49 was supposedly a 400. I got this truck in pieces, not quite basketcase but literally frame sitting outdoors since early 80s and everything else apart in a garage. It's been like a big boy puzzle. It's the first 70s model I've done and already had a 67/68 front clip with it so I was way ahead of the looks curve. I've done square body a bunch and now this and have a 50 gmc showing up this week to go along qith my 50 b1 dodge lol and the 87 r10 and 85 k5 Jimmy

[Paintmycar2]

https://www.dropbox.com/s/6oc8ujoicm...45048.jpg?dl=0
https://www.dropbox.com/s/nw1cxvit8e...45103.jpg?dl=0
Let's see if that works if the images dont show maybe the links will work.

[IronCanine]

Is it a factory high hump cab? 1/2T 2WD 350 engine, my expectation would be that it came from the factory with a TH350 transmission. In that case, I see the M38 on the firewall and the M49 in the cab to be virtually interchangeable and mean the same thing...that being that it left the factory with a 350/TH350 combo. Unless you've got other evidence to the contrary.

[Redneck Rydes]

Some of the numbers on the firewall,are scheduling numbers,when the cab went down the line,they would have the scedule number on it from the build sheet,and if there was a specific option that was needed to be drilled out or somthing installed, it would let the line worker that this was the option,I remember seeing these on vehicles when I worked on the line at GM.