January 30, 2018

GM & BMW 6L80 Family Identification Guide

6L45/50 Early-Style ('10-Earlier) Upper Casting
6L45/50 Late-Style ('10-Later) Upper Casting
6L80 Early-Style ('10-Earlier) Upper Casting

Note: 6L90 Early-style ('10-earlier) also have the exhaust slots like shown above.

6L90 Late-Style ('10-Later) Upper Casting

Look for machined-down boss (A, B, C or D) on the upper casting. Generally, if the A boss is machined down, this indicates an MYA/6L45 (see chart below). This identification system is not foolproof, as some valve bodies do not have any bosses machined down.

Machined-Down Boss on Upper Valve BodyIndicates Valve Body Unit*
"A" Boss IDMYA/6L45
"B" Boss IDMYB/6L50
"C" Boss IDMYC/6L80
"D" Boss IDMYD/6L90
*Note: This is a general rule to follow, but may not always be true. Sometimes no bosses are machined.
6L45-6L90 Early-Style ('10-Earlier) Lower Casting
6L45-6L90 Late-Style ('10-Later) Lower Casting


Upper Casting NumberCenter Support Feed HolesLower Casting Number


'10-Earlier'10-Later'10-Earlier'10-Later
GM6L4594057114Centered95810945
6L5094057117Centered95810945
6L8094040955Offset Front95810945
6L9094040955Offset Rear95810945
BMW6L451590
Centered9581 or 6351


BMW Early Separator Plate
BMW Late Separator Plate

BMW early versus late applications have a separator plate variation in the converter circuit. At this time, there are no known year breaks or external identification features that can be provided.

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