I just finished my TnT. I figured my cost at about $550 for all the parts that are installed on the tractor.
I bought my cylinders from Northern. I bought the top link end swivels from my local tractor shop for ~$10. One was welded on the rod that comes out of the cylinder. For the other end, I had to do some minor rework on the cylinder end, and then welded the swivel to the end.
For the side link, I fabricated a new angled end for it, and welded it to the end of the rod. For the top connection, I left the cylinder alone. Using a clevis pin, I fabbed bushings that fit the tractor and cylinder. All the angles match up with the original components. My original side link is completely intact, just in case I ever need it as a backup or?
The one thing I would look at if I did this again, is using welded cylinders instead of tie-rod cylinders. The tie-rod cylinders I used are somewhat large in overall diameter compared to a comparable welded cylinder. Welded cylinders though, are more $$$.
I did have to lengthen the fixed side link just a bit; the overall centered length of the side cylinder was a tad longer.
I am fortunate that a friend has a metal fab shop. He has torches, arc welders, cutoff tools, metal stock ect. If not for that, it would have cost more to have a shop do the fab work.
One thing I would think about too, is quick connects for the top link. I went to use my post hole auger, and it dawned on me it does not use the top link; I had to bungee cord the top link to the ROPS temporarily.
RobertN in Shingle Springs Calif