I am new to the TRS drive and have a generic question. I have a 1989 Formula 357 with original TRS Drives. What mods would be required to bolt on a set of SSMIII's? I have stumbled upon a used set at a reasonable price and was wondering if they could simply be bolted on to the existing gimbals. The boat has stock 420 motors. Also, what kind of gains in top speed can you expect by just changing drives. Trying to figure out if a drive swap is worth the hassel.

The Ssmiii Drives Will Not Bolt Up To Your Existing Gimbals Tou Would Need To Change The Gimbals As Well. In Addition Your Transom Is Cut To Sit The Drives Very Low In The Water Speedmaster Ii Drives Will Bolt Up To Your Gimbals
But Parts Are Getting Rare And Performance Improvements Would Be Marginal.
Best Case Scenario Is A Set Of Konrads
Hope This Helps

another option is have the drives refreshed. use new bearings throughout change the seals. if your parts are not broken. if you broke or chiped one of the lower gears you can change them to cryogenicly treated gears from merlin marine. I believe they are on oso. Your trs drives are said to handle between 600-700 hp depnding on the boat and how you drive.
If your not going to raise your hp beyond that just refresh them save lots of $$$$ and time. New internals are available through dealers thecases are very scarce. the lowers are known to crack if the gears break. I hope this helps. this is what i have done to mine to help them live longer.

What is the approx. cost of a set of Konrads?

Thanks,

If you are sticking with the stock 420hp motors, no reason to change the TRS. They are reliable, and bullet proof for that kind of horsepower. Pretty stout to 550HP. I had TRS, on my old flatdeck and ran 675HP for 3 seasons, before stepping up to Konrads.

You can get them easily rebuilt (Mel Riggs). No speed pickup by doing the upgrade to SSM. And you will spend an as*load of money.

Ran TRS drives in my 300 Scarab with 650hp twins. Never had an issue with them. Stayed away from hard hole shots. There's still a few guys out there rebuilding them, parts are scarce. #3's are just as hard to find, not much gain to go thru all the work to put them on however you could then use up to #5's with the same gimbles. Konrads would cost you $20K for a pair plus install. I'd freshen up the TRS drives and keep a look out for a set of #2 speedmaster lowers that will work with the TRS uppers. You might pick up a few mph with them. Just my 2cts worth.

Go with Konrads, I did, They bolt right up with no mods. No more drive problems.

I've done the swap, nothing interchanges between a TRS and a III, transom needs to be refilled/cut, steering needs to be external, even the trans tailhousing needs to be swapped.
SSM II lowers will bolt up to your uppers, but wont hold any more power, props are expensive, it will be way too deep in the water, and you'll actually be slower.
Konrads are expensive, but really nice pieces.
Have your TRS drives rebuilt, with 420s they'll last a long time.