The added weight of the cast rear isn't really an issue either way. Just concerned mostly with the axle loads when I'm hanging 400 lbs at the ends of the 3 point arms & 200 lbs on the front of the frame and the aluminum housings holding up. Also figure I can't bolt the 3-point assembly directly to the back of the aluminum case in place of the rear cover like I do on the 169 rear. I'll try to get a pic of current set-up when its light out.

Think you might be better to just mod your 3pt to mount on the 1864 like the original CCC design. Then sell your 169. They are on the rare list, and somewhat sought after

Attachment 96894
Hmmm, not sure I did that right. If it shows up it's the 3-point I built for the old 169 15 years ago or more. Bolts on in-place of rear cover, no other bracing. Will pick up way more than the tractor should with the large lift cyl. The lift links were new this spring, finally wore out the old ones. Arms and top link bracket came from cub add-on that was just partially there at a surplus store. Lift cyl is a shortened cross slide cyl off of a fork lift in the local scrap yard. Circuit spliced into the attachment lift for the 169. Use a little clevis attached to the frame to lock the factory lift into one place when using the 3-point. Works pretty good (has down-pressure too), that's why was looking at just transplanting whole shooting match into the 1864.