Thanks. Maybe others can shed more input?? If this is a LOS 396 RS/SS, with auto transmission, and the only other options taking power is the AM FM radio, console gauges etc, would there be a 37 amp in there or the larger 42 amp? Someone put in a 55 amp 100803 in there now. Don't know where that came from but that's what they did years back. Would courtesy lights in this package require an upgraded alternator? I'm sure that a 37 amp would be plenty for what is there but I just want to get the right one that would have been in there originally.
I did more research last night on the 42amp being used with the TH400 option. I found a similar discussion on a Chevelle site and stated that the 42amp unit came with the TH400 transmission and it was confirmed on some CD a person had that contained option info.
I believe it had to do with the 42a having a higher minimum charge output at idle with the TH400 compared to the 37 amp that came with a manual transmission (unless options dictated otherwise). Looking at the tuneup specs for the 67 w/396, the TH400 idled 100 RPM's lower (700 M/T vs. 600 A/T) than the manual transmission so that is likely why the 42amp, with the higher idle current output, was used.