I have a 86 357 with trs drives. I know they mounted these drives very deep on these old hulls with the poor prop technology. I am thinking about a number 5 conversion to handle my 800 HP blower motors. I realize I would have to change out gimbles but could I leave the position the same, not have to glass and recut the transom. I know the number v's are designed to run alot shallower in the water? From what I can tell it might be just about correct as far as x dimensions bolting the numbers 5's in the same position as the trs's?

It would be a TON of work. Have you considered Konrads? They are rated to 800hp, and parts are readily available. Just pull off your TRS and drop on these. I think they make 1 version that is almost 2" shorter and another that will get you close to 3.5" shorter. There is a pair of used ones in the classifieds currently.

Hey Rob. Going from a TRS to a #5, your propshaft height would be about 6" above where it is now, keeping the engines at the same height. Going to a #3 or #3A would bring the propshafts up around .5-1" i believe. The 3 or 3A would probably work better. I think the #5 setup would be too high.

To do this, you would need different tailstocks on your transmissions, the engines would need to be moved back about 2" give or take. You'd need the ssm transom assemblies. My Fountain was originally a TRS boat, now has ssm, and my buddy's 38 cig was also a trs boat, and now has ssm #3A drives.

If your motors are still out right now, this would be the time to do the conversion. My buddy has the motors out of his cigarette right now. I can measure the exact distance from the original TRS setup holes in the stringers to the ssm setup holes.

I have the rear mounts you would need to bolt your transmissions to the ssm inner transom plate. Its a similar design to the trs, but a little different. Your TRS tailstocks have the mounting holes in them. The ssm plug in tailstocks dont have the holes, so they use ears that bolt to the sides of the transmission, and then the big long bolts go thru the transom plate. I have the ssm #3 Drives still, RH and LH, and also might have you covered on some latham wing plates for the steering setup. I'll have to see if my buddy still has them.

To be clear, you don't need to re-cut the transom if you do this conversion? You just need drives, complete gimbal/inner plate and SSM tail stocks?

Worse case you may have to cut a little out of the existing opening, because the SSM transom assembly is larger. But it's not like it needs to be totally patched up and recut. Im not positive, but if are not changing the height of the engine, most you should have to do is drill new mounting holes for the inner/outer transom assembly.

I have everything that you need for the conversion if you are interested. I even have a set of extension box's for SSM drives. E-mail me if you have any interest.
[email protected]
763-473-8963
612-247-7081

I am concerned with the konrads. It would be so much easier than 3a's or 5's. But if my motors end up at 850hp do I have to baby the boat? Will I be running right on the ragged edge? I just want to be able to feel confident before a 120 mile poker run that my drives will not be the reason I can't finish. Or that I am sweating bullets every time the boat gets air born. Whats the best solution?

Rob I can not answer that but if you contact "Biggus" on the board he is their national sales rep, always answers the phone or calls you back. He will give you the strait scoop. I have a friend that is going to be running them with WELL over 800 hp. Of course in that situation there is no warrantee but I think that they have a few boats running well over the 800 mark. Again Kurt aka Biggus can tell you all those numbers.

Can anyone say for sure how much work is involved to convert a TRS boat to #3s? Some threads you read say that it's a ton of work and others say it's not that bad.

my brother is running 1000 hp blower motors with konrad 540's in his 38 top gun 100 mph all day long in lake ontario waves and no problems at all. go with the konrads and save yourself alot of time and aggrevation my .02