If you look at a #6 transom assembly the flange sticks out a bit .
in my case if I put the transom assemblt directly on the transom the flange would be 1.5" past my transission flange so that wont work unless you move the engines forward.
Thats why the boxes, moves the flange inside the box and then you have room for a driveshaft.

Notice how the flange sticks out :


https://cimg3.ibsrv.net/gimg/www.off...277906204e.jpg

The flange is halfway into box...

https://cimg4.ibsrv.net/gimg/www.off...1879651b50.jpg

Justin were your motors plug in originally? I have all of the Merc drawings for the 5 & 6 drives, plug in and drive line can't scan now its broken, Give me a call if you need dimensions Regards Dan

DAN! that's what I wanted / needed to see, thanks. My transmission flange is about 5-6" away from the inside of the transom. But, looking at that pic, #6 flange (driveline) would be too close for comfort in relation to the transmission for driveline setup. I see why now side by sides or at least the rearward staggered engine runs a plug in tailstock setup. Hence, the use of boxes in your application. I am trying to figure out:

1. IF I can leave engines "as-is" without running boxes.

Q: With plug-ins, the engine and trans have to be aligned to the gimbal almost like a Bravo requirement? I'm spoiled a little because I have 9" long mini-drive shafts on my driveline, very similar to Dan's. they just need to be close within 3 deg to function best without tearing up u-joints.

I don't want more leverage and weight on the back of the boat by adding the boxes. This is what I'm trying to figure out. Best to have a mock-up gimbal and see where things fall.

Yes - boat got put up for sale this AM as I got it back together Sunday after some maintenance and a part failure. Sell it with the 5 setup (great running boat), or keep it and investigate 6s.

Dan - original rigging was with TRS/trans setup, then during the major re-fit back in 2013-2015 the boat got converted to 5s. Engines moved up and forward, prop shaft even with bottom, 5s on boxes. X-dim got changed to what we see above in the 5 with boxes drawing. Converted, it was always setup to run driveline style trans->drive shaft->"carrier" bearing inside the box (SSM tailstock idler)->into the splined drive shaft / input for the outdrive.

https://cimg8.ibsrv.net/gimg/www.off...a2b131af88.jpg
https://cimg9.ibsrv.net/gimg/www.off...7a47481178.jpg
https://cimg0.ibsrv.net/gimg/www.off...2e56482481.jpg


https://cimg7.ibsrv.net/gimg/www.off...84ea5611d8.jpg
https://cimg1.ibsrv.net/gimg/www.off...bcf9c2f6c6.jpg
https://cimg2.ibsrv.net/gimg/www.off...6ef56378af.jpg

Runs #6 boxes with #6 inner transom plates, with the #6 holes welded up on the rear side of the box itself and re-drilled to accept a #5 drive. So - I'm 80% there with rigging if I don't have to "move" anything. Which makes this conversion very attractive.

I can run the boxes "as-is" and fill in #5 holes, re-drill for 6s. BUT - trying to stay away from using boxes. I think it's too much off the back of this boat.

Q: Dan - do you run a driveshaft from the flange of the gimbal assy right to the transmission? No "carrier" bearing?

Question number 1 no you can't run with out boxes and not moving the motors. you best bet is to run the boxes you have and drive line number 6s and you can be running in no time. thats the best case scenario. and the weight won't make that much difference.

quick question. is your box drilled with all three sets of holes on the transom side? and if so which holes are you using ?

Your reasoning for not wanting boxes is flawed.
Props further back will carry the boat better , can go higher with drives , cleaner water , cooler rooster, more leverage to carry the bow, acts like a longer boat , looks cool as **** .
You want the boxes .

Paul lassassa that dumba$$ plumber/scammer/kid apache said my boat would be sinking up to the exhaust holes if I put 6`s on it.
The extra 1400lbs made no noticeable difference that I can see.

The top of the drives aren`t even in the water and my boat is heavier than yours.

https://cimg8.ibsrv.net/gimg/www.off...65113ec49b.jpg

Dan, yes - there are three hole settings. I am in The middle one so I can go up one. Approx 1.0”.