When I acquired my 1957 GMC Napco from my sister, my brother-in-law suggested I try to find and install some front locking hubs. I've searched and searched. I can't seem to find anything which might work with my front NAPCO hubs. Does anyone know correct part #'s and/or brand names I should search for? I've attached a couple of pictures of my front hubs.
Last edited by GrandpasJimmy; 01/05/20251:16 AM.
1957 GMC 100 * Line Built Napco * Pontiac 347 * 89" Stepside * Purchased new by Grandfather from my Father's dealership in 1957. 1967 Camaro RS Convertible 1968 AMC Rebel 1966 Ford F100 Crown Vic swap 1968 Mercury Cougar Barn Find
I meant locking hubs. It has the line built Napco set up including the "Napco" embossed front axle. Apparently during my research, I need to pull a hub off to check the spline count as well. There are some Warn locking hubs out there, just not sure which part #'s I should focus on. Thanks
1957 GMC 100 * Line Built Napco * Pontiac 347 * 89" Stepside * Purchased new by Grandfather from my Father's dealership in 1957. 1967 Camaro RS Convertible 1968 AMC Rebel 1966 Ford F100 Crown Vic swap 1968 Mercury Cougar Barn Find
That design of hub went obsolete a LONG time ago. I'd be surprised to find that anyone makes a compatible lockout to work with it. Back when NAPCO was making 4WD trucks, they weren't toys. They worked for a living, mostly off road all the time, and a disconnector hub just wasn't needed. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Warn locking hubs would be WL-15828 or M-18. The PDF is an old Warn brochure, go to note 1. The Napco drive flange will cross to GMC drive flange 15828.
Once I get the spline count, I'll give them a call. Thanks Ed.
1957 GMC 100 * Line Built Napco * Pontiac 347 * 89" Stepside * Purchased new by Grandfather from my Father's dealership in 1957. 1967 Camaro RS Convertible 1968 AMC Rebel 1966 Ford F100 Crown Vic swap 1968 Mercury Cougar Barn Find
Jim, thanks for the part numbers. That really helps as It gives me a a starting point. I utilize "searchtempest" and found a set of Napco M-21 on Craigslist in Los Gatos,CA yesterday ($2,000....yikes). Hopefully, IF I ever find a set of m18 they will be somewhat reasonable. If anyone stumbles across a set, let me know, Thanks!
Last edited by GrandpasJimmy; 01/05/202512:21 PM.
1957 GMC 100 * Line Built Napco * Pontiac 347 * 89" Stepside * Purchased new by Grandfather from my Father's dealership in 1957. 1967 Camaro RS Convertible 1968 AMC Rebel 1966 Ford F100 Crown Vic swap 1968 Mercury Cougar Barn Find
FWIW - Here is a free PDF of an early Warn Manufacturing document that gives a bit more detail about the various locking hubs for many vehicles, including the GMC Napco equipped trucks. Just a bit more info to add for anyone interested.
~ Dan 1951 Chevy 3 window 3100 Follow this story in the DITY Gallery "My Grandpa Carl's Truck and How it Became Mine" 1966 Chevelle (Wife's Hot Rod) | 2013 Chevy Silverado (Current daily driver) US Army MSG Retired (1977-1998) | Com Fac Maint Lead Tech Retired (1998-2021)
Dan: Good info, thanks. My experience with the NAPCO stuff is that you need to know exactly what you want. It appears that configurations for the same year can vary just enough to make a difference at times. I thinking that at the time NAPCO (Northwest Auto Parts Company out of Minneapolis) was not exacting in documentation. don
I pulled the 8 bolts and center bolt off the end of my 1/2 ton hub. I now have a better understanding of what I need to search for. Mine is a 16 spline, 3 5/8" outside diameter hub with eight mounting bolts. Not much out there other than a couple of them being rebuilt on youtube. Anyways, like my search for a 1957 GMC Operator's Manual (comic book style) continues, so will my search for these obsolete hubs.
1957 GMC 100 * Line Built Napco * Pontiac 347 * 89" Stepside * Purchased new by Grandfather from my Father's dealership in 1957. 1967 Camaro RS Convertible 1968 AMC Rebel 1966 Ford F100 Crown Vic swap 1968 Mercury Cougar Barn Find
If you happen to have a dep pocket and a very skilled machinist handy, it might be possible to adapt something newer and more available to your hubs. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Jimgmc, Thanks for the info....I'll be calling them Monday morning.
1957 GMC 100 * Line Built Napco * Pontiac 347 * 89" Stepside * Purchased new by Grandfather from my Father's dealership in 1957. 1967 Camaro RS Convertible 1968 AMC Rebel 1966 Ford F100 Crown Vic swap 1968 Mercury Cougar Barn Find
