Not sure if this will help a whole lot but this seems to be a fairly complete (yet generic) listing of the codes:

http://home.cyberia.com/~jprogers/rpocodes.htm

To answer you question and to help answers everyone'* tranny questions. ALL GTP'* and SSEi'* have the Heavy Duty version of either the 4T60E-HD or 4T65E-HD depending on year. ALL the rest (naturally aspirated) have the regualr one without the -HD (heady duty). Please stop asking these questions.... Its been beaten to death and just do searches...

Sorry to upset the crowd.

Lets see, i searched on this board, clubgp, efi-street, w-body, 3.4 yahoo, asg, cadalic yahoo, 60 V 6, the lumina board, tgp, wasakie'*, and gmforums (thats 13 boards btw). And I found out that my car has both the normal 4t60, and the HD 4t60, at the same time. Nobody can seem to agree which one it is. The 2 engines that I know for sure got the HD version is all the Cadillacs (they just ignored me when i asked), and the 3800 II */C 95-96? years before they came out with the 4t65. I know the Bonneville had that engine, so I am here asking for RPO codes of anyone that has one of these HD transmissions; i did not ask which one I have cause that would get me nothing but the same disagreement.

Well brian! Send me your VIN and all the "L" & "M" RPO codes and I'll tell for sure what you got! Send it to: deathrat64@yahoo.ca

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Sorry?? don’t be sorry I think yours and any question is a good one I remember asking the same questions only a year ago when my tranny blew. Ask your dealer, but there is a very knowledgeable yet frustrated fellow telling you the truth. In most cases unless someone messed with your ride you will have a 4T60-e with an l36. Yes the Cadillac’* all came with 4T60-e HD. Yes the sc 225hp l67 received the 4t60-e HD. 95 was definitely a 4t60-e. or 4t60-e HD. Oh the HD internals are basically beefier and the final drive is different. Oh and if you want an EXTRA BEEFY 4T60-E HD I can get you one.

TY

I have my original RPO code sheet scanned, and once my website goes back online I'll post a link to it. But it says trans: M13-PBW. I understand that some questions get asked a lot, and it is frustrating, but I was just proving that i did take the incentive and search it out already, and didn't find what i needed.

How extrememly beefy is extremely beefy. I can get an ASG 4t60-e hd that is modified to handle 300-400 hp and equal torque of their caddie 5.0 v8 engine, for the tune of $3000. Has better final drive gearing, ~3.83 compared to my 3.43.

This is all planning for the turbo project that i am starting. With the tranny barely able to hold the engine now, i can't imagine what 300+ hp will do to it, with the torque peak occuring right at the shift points too.

M13 = 4T60-E Hydra-Matic Transmission which is the standard trans for the Bonneville SE &SSE w/o SC 3800. The other "M" RPO should be MXO = 4 Spd OD A/T. The "PBW" part I'm not sure of!

Well, after looking it over again, MX0 is on there, just not in the same spot. I feel smart now. So were all 4t60-e'* RPO M13, and the HD version just an option (MX0)? Does anybody know what "merchandising option" mean (is the MX0 RPO)? You know this is not good if I already have the HD version :(

Brian

Yes all 4T60-E'* were M13! The MX0 RPO just defines that this trans has an Overdrive! It'* GM"* way of being redundent! I do know that the 4T60-E'* were available for all NA 3800 Series I & II'* combos from 1992 to 2002. The 4T65-E'* were available for all SC 3800'* from 1992 to 1994 and the 4T65-E HD from 1995 to 2002 on all SC 3800 Series II'*.