The Stovebolt Site Forums The Shop Area Driveline How to ID a single-action and double-action shock?

How can you visually identify a single v. double-action shock. I have a 1949 3800 dually. I know the double actions were an option.

Also, I saw for sale on Chev's of the 40s shock absorber fluid. Never had seen that before. Is that the correct fluid that should be replaced in those shocks? Any way to know if they need a rebuild? Anything to look for in the way of function/maintenance/rebuild?

Dumb questions just never had to deal with any shocks like this before.

This may be helpful
https://www.stovebolt.com/ubbthreads/ubbthreads.php?ubb=showflat&Number=411380
Use the search function for more this site is amazing.

Double action are easy to spot - they have a screw on cap on both ends of the shock. I watched for years on ebay before I got a pair. I would look for the caps in the ebay picture, then would check the part number. Be sure to look up the part number out of the Master Parts Catalog. It lists the Chevrolet number plus the Delco number. The double acting shocks look similar for the 1/2 ton vs larger trucks but they have different part numbers.

Steve, I always try and search (and I did) before posting. Your search proved more fruitful than mine did.

Dave, That helps.

Anyone know about the fluid that is sold? Is it very specific to shocks, or is it just something repackaged that I already have on the shelf, such as a light motor oil, PS fluid, etc.

Things to look for regarding function while they are off the truck?

I have used motorcycle fork oil seems OK. And it can be had in different "viscosity" ratings. Not expensive. I think ATF could be used as well. Any thoughts out there? Clean and fill. Move them and look for leaks. Move them and see if the fluid level changes, that is a good thing, you are moving the air out. Single action shock will have resistance in one direction and double action shock will resist both ways.I just changed a set on a 48 Stylemaster. The hard part was the Caster, Camber adjustment. Not an issue on the trucks.