MSD 6BTM vs MSD 6A....what are the differences??

[BlueOvalStangGT]

I currently have a MSD6btm with no boost anymore. My buddy has a MSD 6a and he wants a 6BTM. I was gonna trade my 6BTM for his 6A/a bottle heater and some cash. Anyone see anything wrong with this? Do they have the same plugs? The only difference between the BTM and 6A is the spark retard thing right? Anything else?

 

[brothergoat5]

The 6a has no rev-limiting capabilities. You can send it to MSD and they will convert it to accept an external rev-limiter (part# 8738 FYI). Last time I checked the cost for that conversion was about $35.