Thanks!
The steel tubing I bought will return my back axle to as it was built originally. I'm notching 3.5" SQ tubing to saddle the rear axle and use the axle holes left from the original stringer posts.
As it sits now it's got 200lbs of steel gizmos that somebody fabricated to make into a dump wagon.
Given that these David Bradley gears have the bolster that swivels R&L on top of the one axle I'll need to allow for that sideways deck tilting movement when I choose my tire clearance via the stringers height- by lay a board on the bolster using spacers to see what it gives me out at the tires larger center tread OD. The old stringer remnant was nearly 7" wide oak and no other wood was left behind.
My build sites remote and small work space around my foundation so a tight turn up there and a steep & twisty woods road up there near the ridge top, so a long wagons not gonna work. My longest materials will be 16' so 14' deck seems best.
My tongue "looks like" the green one above.