The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - What were the stock manual trans options for these trucks?

kipps · 03-13-2021, 12:15 PM

Correct me on this info where I'm wrong. I'll go back and edit the post so no one gets bad info from it.

1. The MM3 rpo code designated a truck with a three-on-the-tree transmission.

2. This MM3 rpo code could have either of two Muncie transmissions; a m62 or a m64.

3. (was one of these the "heavy-duty" version that poster "d13" mentioned?)

4. Both of these transmissions were side loaders, and were only available on the 2wd trucks.

5. The four-speed np440/np833 was available behind the diesels and the smaller gas engines as a fuel economy option. This transmission didn't have the deep unsynchronized first gear that the sm465 was known for. It did have an overdrive gear.

6. The np440/np833 could have had an iron or an aluminum case on the 2wd trucks. The 4wd trucks were iron only.

7. The bolt pattern was partially different between the np440/np833 and the sm465. Some, but not all, 1980's bellhousings were cast and drilled to fit both patterns.

8. Did the m62/m64 transmissions share a bellhousing pattern with the four-speed transmissions?

03-13-2021, 12:15 PM	#4
kipps Registered User Join Date: Jul 2014 Location: North-central Virginia Posts: 1,099	Re: What were the stock manual trans options for these trucks? Correct me on this info where I'm wrong. I'll go back and edit the post so no one gets bad info from it. 1. The MM3 rpo code designated a truck with a three-on-the-tree transmission. 2. This MM3 rpo code could have either of two Muncie transmissions; a m62 or a m64. 3. (was one of these the "heavy-duty" version that poster "d13" mentioned?) 4. Both of these transmissions were side loaders, and were only available on the 2wd trucks. 5. The four-speed np440/np833 was available behind the diesels and the smaller gas engines as a fuel economy option. This transmission didn't have the deep unsynchronized first gear that the sm465 was known for. It did have an overdrive gear. 6. The np440/np833 could have had an iron or an aluminum case on the 2wd trucks. The 4wd trucks were iron only. 7. The bolt pattern was partially different between the np440/np833 and the sm465. Some, but not all, 1980's bellhousings were cast and drilled to fit both patterns. 8. Did the m62/m64 transmissions share a bellhousing pattern with the four-speed transmissions? __________________ 1987 C6P V20 truck, 2010 LMG 5.3, AFM delete, 2010 Camaro exhaust manifolds, 1997 nv4500, 1991 np241c, hydroboost, 2005 14bff axle & driveshaft, drop-n-lock gooseneck, 4.10 gears, stock suspension, rims, and tires. Still a work in progress. Any questions or suggestions are welcome!