The Stovebolt Site Forums The Shop Area Name that part ... 1941 1.5 ton extra bolts

Hi.

Just finishing up an engine/transmission rebuild/reinstall. I have 4 bolts left over that somehow weren't labeled.

3.5 inches long. About 1/2" in diameter. Any clue what they could be for? Engine is in, tranny/bell housing/tranny mount bolts all accounted for.

They were at the"beginning" of the disassembly parts order, sitting next to the grill if that's any help. They are geesey, which makes me think "lower" in the truck somewhere. They are big enough I don't want to discard them.

Front engine mount bolts?

I have the 4 for the front mount plate already directly under the crank pulley. Two are connected to the block and two are carriage bolts that go into the mounting plate. Unless there is another I'm missing?

My guess is they are newer bolts used for lifting/alignment, etc. They don't look like 70 year old style bolts.

Steering gear to frame bolts???

Nope, never removed the steering box.

They are dated PA on the head of the bolt... Which Google says is period correct to the 40s.

Can you check the thread count/measurement. Chevy used very few bolts in the engine area that were around 3-1/2" long from what I can find in the parts books. I can find bolts listed in the 1929-46 Chevy Master Parts Book as 7/16-20 x 3-1/2" and a 1/2-13 x 3-1/2 in the general hardware list, but neither match engine mount bolts for your truck.

For your truck, there is an engine mount bolt listed as "Bolt, rear hold down (7/16-20 x 3-3/4 drld.) GM# 594121 with a requirement of two (2) bolts, but that sounds different than what you have pictured.

There is the possibility your existing bolts were used to replace other similarly sized bolts.

The shaft of the bolt is 3.25 long. 3/8 in diameter. Course threaded.

The two rear tranny mount bolts are already in place.

Did you have a donor car or other extra parts that they could have come from?

I guess I missed that we are discussing the work on your '41 GMC 1-1/2 ton.

Let me go back to my GMC resource books to see what I can find using these more specific dimensions.

First, on the "PA" head marking, from what I know that just designates a manufacturer and has nothing to do with grading. If there are other markings, like lines on the head, those would indicate a specific grade of bolt.

Scouring through a 1939-41 GMC Master Parts Book for Models 100-460, there is no specific individual hardware part number to dimensions listing. Knowing that Chevy and GMC shared a lot of the same designs and hardware uses (and part numbers), I looked in the earlier Chevy Master Parts Books for similarly sized hardware and tried to compare between brands to locate a similar sized bolt and where it's listed for use.

The only thing I found that seems possibly similarly sized in the front end/engine compartment vicinity for the 1-1/2 ton trucks is for the front springs "spring retaining clips". The bolts (I believe the GMC book calls for 8) spans the width of the front spring to secure the clips to the spring packs. I believe there are 4 spring pack clips for each side.

Perhaps these came from the front springs???

? Shock mount bolts??