This morning my mechanic installed an MSD HEI Upgrade kit on my '79 L-48.

The only real advantage to an MSD or any brand capacitive discharge box is maybe improved starting.  It really doesn't offer any real world advantage for a street car.  It might help a points distributor some but that's arguable.

did you mount the spark box inside the corkpit, as hot as the engine compartment gets, its best to keep it away from the heat.

I did mount the 6A behind the passenger side of the dash.  I'm not sure if that location is as doable in a '79...you have the glove box taking up much of the necessary room.  It may be...I just don't know.

The MSD set-up definitely helps with the starting, but the one thing a lot of folks don't notice(or pay attention to) right off is how much better the idle is most of the time.
You may not actually feel any seat-o-da-pants improvements, but an emissions test will prove it out very nicely. The fuel burns much cleaner, and more completely, with the MSD.

I've never had any luck with anything from Mallory, except for the old magnetos...those were kick a...
Adams' Apple2009-06-29 20:21:09

Yeah! I was thinking of sending the Mallory back to them with the tow bill from last summer and the reciepts for the three ignition modules I had to replace on it.

MSD spark box's can die to, thats why NASCAR racers have two box's in their cars, heat and vibration  is the # 1 factor, if you are on a run somewhere hundreds of miles from home your in a world of hurt if the box goes out,  when electronic igns first came out, MSD wasn't born yet, GM was just starting to put them in new cars and the first aftermarket one I saw was Mallory, and Mallory in 75 had great products, so I went out and bought the whole Mallory package , electronic tack drive dist and spark box for my L36, well the spark box's lasted about 2500 miles each, Mallory replaced two of them free of charge, I put the point setup back in and tossed the Mallory, It was partly my fault anyway, I mounted the box under the hood and they didn't mention anything about heat, this time around I went with  hand built custom tack drive HEI by a company called Davis Unified Distributors out of Memphis Tenn., you call them and they ask what the car's Wt, Cam specs., cu in, compression,  rear gear, carb, trans, and how your going to use it and they build it with their 50KV performance modual and coil Street to 7K Race to 10K if I remember right, and the best part is if the modual, coil, rotor, cap gives out I can replace it with stock HEI stuff to get me where I'am going or get me home. I ran the race setup in my dirt modified on alky with 140 jets all around in a worked over 750 holley double pump with no problem. anips2009-06-30 06:27:14

I have the MSD in my car and it does start a lot easier then before. Not on the road yet yet so no comments about speed performance yet.      Many a moon ago I had a 1972 Pinto with a Mallory dual point distributor in it.  Once it was set-up correctly it never needed a points change in it again. I just filed down the point contacts once in a while.  It ran great untill the rear springs rusted thru the trunk.

I've got an MSD distributor with a 6A spark box.  I mounted the 6A on the back of the left front wheel well.  You can see it through the left gill vent.  No problems even in the Texas heat.  

No box on this one. It's simply an MSD brand HEI Dist.