Hey guys, I have an older 9.5 go-devil (briggs) I'm thinking about swapping out the tired old briggs for something new and keeping the same frame. Has anyone done this? I'm wondering if it is a pain in the butt.

Yea you can do it. Make sure the shaft height Is the same ( mounting plate up to the center of output shaft) that way you dont bind the U joint and,, check shaft OD.. Was thinking bout doing the same with my old 9hp by maybe putting a 12 on it but never have got around to it or checked on the shaft height to see if it was different... Someone else on here may can tell you more. But thats the only 2 real issues you would have I think... May have to change up a bracket or two, But not much to that.. The way them cats down south are building up their Big Blocks, may be just as cheap to rebuild the Ol 9hp and make it a 12 or 16...

I emailed go devil about this and the owner (Warren Coco) called me back. i have a 1986 8 hp briggs and i wanted to put a 13 or 20 honda on it. he said it will work but you will have to change the prop to the proper pitch otherwise you will overpopwer the prop and not run at the full potential of the motor. there was also a issue with the key on the shaft he talked about but it didnt sound like it was a big deal. i have not swapped mine out yet. he told me to call him when i did and he would give me more details.
i would give them a call and talk to them. not to many companys out there any more that the owner will call you back. good luck and let us know how it works out.

We put a 18hp Van on a GD Crawfish 9HP frame. Shaftsize on 9-18Hp are same and same height to center of motor output shaft. Key way was also the same, some older GD frames had holes already drilled in motor mounting plate to same spacing as Twin small block vans,You will need to replace prop for sure. 18Hp used a 9x5 MB LT Prop with good results. Since this swap we have modified this same frame to 29HP big block. We had to add steel to motor mount plate and drop it at up-down pivot point 1" to accomadate taller motor output shaft height, and longer wider motor base spacing. Motor keyway has to be broached out to1/4" in universal yoke to accept larger output shaft keyway. A new motor mount on upper frame needsto be fabricated for wider hole spacing on big block motors also. Wehad to cut some metal away from transome mount to get full side to side swing while pivoting motor up and down this was do to lower ing motor mount plate 1". We are useing a Hopkins 9x8 prop on this rig which is on a 14'x48" Lowe Jon with good speed and 3650RPM with 500# load.