Hello all. I just found this site recently because I was looking for some information on my swamp buggy. I realized that I have a complete running driving Napco. Has a 270 engine that still runs over 50# oil pressure. 4 speed. 114” wheelbase. The complete original drive train . From radiator,engine to exhaust pipe . I bought it 35 some years ago and turned it into a swamp buggy. Now I realize what I have. I am trying to figure that out. I have some pics but need some direction as to what and where to look or otherwise identify this truck. I did replace the water pump n carburetor. And made new cork gasket under the fuel bowl. The carburetor is from the factory in California that was the little old lady shop. I still have all the original parts. Including the muffler n tailpipes. If that can give you any idea of the condition. Other than that it is all original and still runs n drives good. For an old GMC. I did put a match set of Dana 60s under it because I needed the 3/4 ton axles. The 1/2 ton axles are not strong enough for my needs. So the napco axles are off the truck and hanging out in the back yard. Nice n safe. I will see if I can get time to pull them out and cleaned up so I can get better pictures. I was going through my stuff because I need to thin down. And I want to build a different buggy. With power steering n automatic transmission. So my beautiful wife can drive to easier. So all this stuff will be for sale. Any help appreciated. Thanks man
It doesn’t have the oem radiator in it but I have it. It had a leak. And I didn’t want that old of radiator out front on a swamp buggy. They get damaged.
Should be an engine serial number stamped on the flat surface of the block just towards the rear of the engine near where the distributor goes into the block.
Hello Bill, thank you for all your contributions. They have helped me already. Guess I missed posting the engine stamp picture. But all I could see was 270 . I will remove the paint on it and double check.
Might be a service replacement block. They came from the factory with just the first 3 digits (the engine size) stamped so the installer could copy the rest of the digits from the motor that was being replaced. Back in those days some states used the engine serial number on the title instead of the chassis number from the cab. Worked OK until you swapped engines.
Thanks Bill. So , how do i identify this truck ? Wheelbase , engine size, 4 speed, the number of leaf springs ,I can get better numbers on the transfer case because the nomenclature plate I’d still attached. Was thinking of narrowing it down by using the charts on serial numbers that Rob,old gmc parts, posted. Is he still around? If this is an engine where you can add numbers, would this help folks who have there trucks and no title? Because they used serial numbers from the engine block. For someone who doesn’t have a title? Seems that a person could add the numbers in. From whatever body was on it . To match them. Does that make sense ? Trying to figure out my options on this truck. I’m glad that I realized what this truck is. It would have been a shame to let her finish out as a swamp buggy. Although she is one tough old gal. I could drop her in low low n just let her chug. Kinda like an old JohnDeere. I needed more clearance n tough tires so I welded the wheel rims into the inside of 9.00 bud style truck rims. Well actually old military tires n rims from a deuce n a half. Worked good till about the fifth wheel hop. Broke a front axle but I have parts. This is too good of an old truck. And I’m a car / truck/ tractor old stuff kinda guy. There are folks who will treat her much better who can use her. But I need to I d . So any suggestions are welcome.
Rob is very much still around. If you haven't already joined the forum he runs, I'd recommend it to any old GMCer. Try http://oldgmctrucks.infopop.cc/eve Wheelbase: 1/2 ton GMC were offered in 114" and 123" wheelbase. The 3/4 ton was only 123". 1 ton GMC were offered in 114", 123" 135" and wheelbase. I'm no NAPCO expert, but I'm pretty sure they dealt only with the 1/2 and 3/4 ton models. Wheels: Again, no NAPCO expert, but I think they stuck with 6 lug wheels on the half ton and 8 lug wheels on the 3/4 and 1 ton. Engine size: 270 was the only 6 cylinder engine size offered in the smaller trucks (up through much larger 410 series) from '56 through '59. Yes, the semi-blank engine serial was to help with title problems when the existing title used the original 270 engine serial number as identification.
