Identifying transmission

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7Brandon07

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I got a 91 5 speed standard I understand they used a few standards on these trucks wandering what mine might be the bell housing is integral to the unit and it has a waffle design
Thanks
 

Matt Conner

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Is the nv3500 the same as the hm290?
Though the hm290 (5lm60) and NV3500 look virtually the same on the outside, the internals are different, like the front and rear bearings, the 5lm60 has 3 shift rails and the nv3500 only has 1, they are interchangeable but if it was me I’d use a external slave nv3500 instead of a 5lm60, the nv3500 is less prone to failure, basically the 290 sucks compared to the NV 3500
 

7Brandon07

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Damn hopefully I got the nv3500 I read somewhere they started using it in 93 though and I have a 91 but I also read elsewhere they started using in 88 so not sure
 

7Brandon07

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Which digit is the transmission rpo code anyone know ? I noticed most of them start with a M I only have two pro codes that do mg5 or mm5 mg5 is a top code for a getrag 5 speed I know m50 is a nv3500 not sure if I’m looking at the right digits in my sheet
 

east302

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Hopefully this is legible, it’s for a 1991 and gives the RPO code (but not the specific name for the transmission)

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7Brandon07

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From what I’ve been reading I’m assuming it’s the 5lm60, well now i know not to bother getting this one rebuilt, my plans are to either rebuild the 305 or get a rebuilt 350 one day do the same with the trans but seems it’s much better to get a different trans when this all happens, what’s a good trans to upgrade too ? I know the nv3500 isn’t the most liked either.
 
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