Thanks for the info paralyzed. I have both the Gorillamaxx single speed and I also have a 4 piece aluminum emaxx trans. The only problem is I planed to use the 4 piece in another build and I have already used the Gmaxx in one truck and my goal is to have a different trans/center diff in each truck I build.

I think the only way for it to work on this chassis is to have the widest point of the gear above the chassis. Determining what mount is my challenge now I guess and then I will be able to see if it is going to put the gear in the right place. I'm also considering making my own mount to suit all of my needs and then I won't have to buy any unneeded items.

Getting the centerline above the chassis you are gonna run into driveshaft angle problems. The driveshafts will rub the chassis if the diff is too high.

I just learned the losi 8ight 2.0 center diff has a plastic spur that comes in 43 tooth. Maybe that will be the answer.

Get a measurement between chassis rails, then you can use BrianG's app to know the diameter of a particular gear. It shows a 43t spur gear is 45mm wide.

app here > http://www.scriptasylum.com/rc_speed/gear_calc.html

Thanks Paralyzed for all the input. Driveshafts rubbing the chassis is a major concern. Looking back at Greggers build with the Gmaxx and a center diff his shafts looked close to rubbing. The HCR chassis doesn't have the same amount of room where the cutout is for the trans as the Gmaxx, so this could be really close.

I measured between and came up with 1.780 possibly + a few .001. Kept it on the small side though to get a better idea if it would even be close. Worked it out and came to that equaling 1.780inces=45.212mm. That might actually work. I guess 43t will be the max number gear I can go with. I have an Ofna center diff on the way now, but I'm not sure what they have to offer as far as teeth choices. I will start researching that now. Losi might be the winner, I just wanted an ofna because I wanted a metal cup on it, which I have spares of.

Losi Ten-scte 40 tooth center diff > http://www.ebay.com/itm/NEW-LOSI-TEN...item51a449dc2d

Man your good paralyzed, thanks. I have diffs on the way now to start seeing what I can come up with.