MSD 6A rev limiter possible?

I've decided after having my 6A box for several years that I need a rev limiter. Is there a practical way to do this with the 6A box? I would rather not buy and wire in another box, but if that is the best or only way, then I'ld do it. Thanks!

Is there a plug-in on the side? There's a separate rev-limiter box from MSD that just plugs in, as I did on my 6T.

I sent my 6A MSD box in and they converted it to a 6T. I had this done in the late 90's and it was $30.

you have to have a 6T/6TN/6HVC for the 8738 rev limiter to work. I actually have the stock ignition and the 8728 rev limiter, but that won't work with the 6A either.