Please excuse my ignorance, but I'm not sure what you mean by mid steering shaft. Thank you.
My bad for not explaining..... mid steering shaft connects the steering column inside cab (through cab) and to steering box. So you’ll see the mid steering shaft as soon as you open hood and look below brake booster. You’ll see it has a slip joint where it can lengthen and shorten along its length, gab at this point and wiggle laterally there should be no play (but I’m thinking there will be). Next rotate as if you were steering the truck engine off key out of ignition, there should be no play (again there will be I’m thinking).
Ok to fix... ideally purchase Borgeson mid shaft and toss the stock one, it’s a poor design and prone to sloppy steering. Short term you can reshape the groves in the slip part of the joint on the stock one by using a chisel and hammer to reshape the grove and it will tighten somewhat, but it’s a short term fix, you’ll need to pull off truck for this. Undo inside cab and at steering box, collapse to get off truck, reshape and re instal. Replacing with above noted is the ticket. The Borgeson is pricey, but well worth the cost MO it’s a quality piece and rebuildable.
Steering box can be adjusted to remove some of the play, just be careful to not over tighten the box. Too tight and steering wheel will not auto recenter after driving around a corner. A Red Head or Blue top are proported to be top drawer steering boxes, it’s on my list.... just down a ways.
Just did a PMF SRK (3.5” lift) on my Tan White Tan truck with a D60 swap V codes SD springs, anti sways front and rear along with Borgeson. Have stock springs in rear, plan is to install late model SD 2011+ on the rear as they are way longer and ride awesome and I’ll leave my air bags to level it up. It handles and rides remarkably better then stock.
Cheers,
jrc