The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post

**G&R's57GMC** · 12-26-2014, 04:05 PM

The NAPCO conversion could be installed on any truck with whatever was on the truck.

So yes you could have a NAPCO with 3 on the tree, with or without O.D. , 4 on the floor or with a Hydramatic .

BTW the Hydramatic does have Park, to engage it you would put it in Reverse and when you turned the key off the PARK plunger would engage .

Does this seem odd to you today ?

Well back in the day it was common practice to put a MANUAL trans in Reverse when you parked.
So it wasn't a far stretch for GM to have the driver put the Hydamatic in Reverse.

Generally Reverse was the lowest gear in a manual trans and it would have a harder time turning the engine against compression.

More then a few vehicles ran away on hills when the driver didn't also set the parking (emergency) brake.

12-26-2014, 04:05 PM	#7
G&R's57GMC Senior Member Join Date: Aug 2010 Location: Shasta Lake, CA. Posts: 1,624	Re: NAPCOs with Automatic Transmissions? The NAPCO conversion could be installed on any truck with whatever was on the truck. So yes you could have a NAPCO with 3 on the tree, with or without O.D. , 4 on the floor or with a Hydramatic . BTW the Hydramatic does have Park, to engage it you would put it in Reverse and when you turned the key off the PARK plunger would engage . Does this seem odd to you today ? Well back in the day it was common practice to put a MANUAL trans in Reverse when you parked. So it wasn't a far stretch for GM to have the driver put the Hydamatic in Reverse. Generally Reverse was the lowest gear in a manual trans and it would have a harder time turning the engine against compression. More then a few vehicles ran away on hills when the driver didn't also set the parking (emergency) brake. __________________ Glen & Jane's Rides ‘57 GMC NAPCO Long Bed V8 4 speed Bought 2008 7 other cars & trucks , 5 trailers '56 Chevy Long Bed I6, 4 speed Bought 1990 Sold 8.22.2020 ’56 GMC Suburban Pickup V8, 4 speed Hydramatic Bought 1996 Sold 10.11.2020 My Other Tinkerings http://67-72chevytrucks.com/vboard/s...75#post8967275 Last edited by G&R's57GMC; 12-26-2014 at 04:26 PM.