As Paul Wood told me, "Just remember that no good deed goes unpunished."
Just for everyone's FWIW, JTACO is the "supplier" that had issued an inventory list to me stating they had 318 of the eyebolts in stock, ready for purchase. They have a minimum order fee of $60. (Who would want to pay $21 for a bolt, then an additional $39 for the privilege of buying it, and then pay freight on top of that?) So I offered to buy all that the membeship wanted, pay for it all out of my own pocket, and then ship them directly to each member via U.S. Priority mail ($3.95) charging only for each members actual cost.
I received the first group of 35 members requests virtually overnight, and an additonal 26 have trickled in since. When the first 35 came in, I called JTACO and placed the order. They acted very confused and told me they had only 4 on hand. I protested to them that only the week before they'd stated they had 318, and they responded that yes, their inventory list shows that, but they can't locate them in the warehouse. I began to worry that some might feel disadvantaged if I'd placed an order for the original 4 and expose myself to charges that I'd on my own determined who'd receive them, so I instead obtained a promise from JATCO they'd hold the 4 and would outsource for the rest of TIC170A's order. I began a search throughout the marketplace looking for alternative suppliers, and meanwhile notified all members who'd placed orders of the situation. (When I called back in a couple of days to see if they'd located their inventory, I found you'd obtained your order from JTACO directly and they'd sold their other 3 also. Apparently they don't do what they say.)
I have located a hardware supplier in MS that promises to produce the bolts at the agreed price, and I am waiting for his notification.
Meanwhile, back to your towbar question--
I've seen several towbars that worked well and a few that didn't. The best ones used 1.5" square tubing with spring loaded clips at the aircraft end. A homemade one that worked well used locking "hitch" pins at the aircraft end, which penetrated circular "ears" on the outside surface of the square tubing. The weight of a commercial unit I've seen was all that held it attached, but I would be uncomfortable with that arrangement not only because of lack of attachment security, but also because of the weight of the entire unit. (It was designed for very large aircraft and had pnuematic dollys on the aircraft end.)
If you can find a DC-3 or D-18 on the field somewhere, you might look at the maingear towbars used for them.
I"ve cast about for an original L-19 towbar, ex-military/surplus but have been unable to locate one. Any Air Force or Army types out there that used these in Viet Nam or Korea?
And I feel traceability is important.)