I know little about the Merc 3 drive.
I'm looking at a boat with them, and want some real opinions.
First- How do you tell a 3 from 3A? What's the diff?

Is it even worth buying a boat with 3's?
Does Merc even make the 3 any more?
Parts?
Word is that they're reliable..

The boat is very nice... but what about the drives???

The #3SSM's are not made any more they were replaced by SSM3A's. Here is a description of the 3A's:

III-A SSM
The III-A Super Speed Master (SSM) drive is a veteran of Mercury Racing drive stable. An updated version of the Mercury Racing III SSM drive, the III-A SSM drive features larger vertical bearings in the upper housing. The larger bearings provide increased rigidity for the driven gear, resulting in increased bearing capacity and longer life. Larger driveshaft splines provide greater strength, while larger pinion bearings hold lower bevel gears more rigidly, resulting in increased bearing life. A larger propeller shaft increases drive strength and is rear loading for improved shaft contact with the propeller. An extended “nose” on the gearcase improves water flow and boat handling.

Features & Benefits


Large driveshaft splines provide greater torsional strength.

Large vertical bearing in the upper housing provide increased rigidity for the driven gear and longer life.

Large pinion bearings hold lower level gears more rigidly resulting in increased bearing life.

Large propeller shaft is rear loading for improved shaft contact with the propeller.

Input ratings are 750 HP and up to 750 foot pounds of torque.

Extended nose on the gearcase improves water flow and boat handling.

Drive-line and plug-in models available.

Transmission required.

Counter rotation models available for multiple engine applications.

Gear ratios: (RH or LH) 1:1, 1.18:1, 1.33:1, 1.48:1 or 1.62:1.

You may want to look through here at some of the pricing as compared to other drives; while they are reliable...the ain't cheap to fix

drives

How do I know if the boat has old 3s or 3As???
Boat has 700+hp, so std Bravos are not an option. XR conversion would cost more than the hull is worth...

I think you can tell the difference by the diameter of the prop shaft. Call Doller offshore in Ft. Lauderdale...they can tell you.

timg,
I have speedmaster 3a's on my 357, never had a problem, smooth as hell when shifting, you don't hear or feel nothing

Count the splines on the prop shaft. 19 and it's a III, 26 and it's a IIIA. There are some other differences, but that's the easiest way to tell.
No, IIIs are not made any more. Not too hard to find parts for though. I think IIIAs are still in production.
Great drive, I would take that over any Bravo package with 700 hp.
Gary

I had Mel Riggs in Fondulac rebuild a 3A for me last summer. Parts aren't a problem but after paying that bill I'm pretty careful about checking the drive oil for contaminants. Water, specifically.
Check to see if the boat has upgraded Borg-Warner transmissions. Stock units might not be 700HP-friendly.

OK, I asked the sales guy to count the splines on the prop shafts.
3As.. maybe. I think I'll stay away if they're old 3s...

Thanks for the help guys... it's much appreciated.

Are you turning 3 or 4 blade props? Boat is over propped and will need a different set....

Tim G, I think I might know what boat you're looking at... would it possibly be a "smoking" ride out of the midwest? If so, I'll have to kill you - I've been wishing and dreaming about that one for a while now...

Of course, if I'm wrong just ignore me!