motorjock:
<font color="blue">I have a TN75 and would like to go to a 75D. </font>
Gee . . . sure wish I had a TN!
<font color="blue">How big of a hit did you take and was it worth it now or wait until you have more equity in your tractor. </font>
The longer you wait, the bigger the hit (unless, of course, you expect it to become a collectors item in the near future). The amount of "hit" you take is irrelevant to the amount of your "equity." Whether you own it outright, or, share ownership with the bank its worth what its worth. You've already taken whatever "hit" you are going to take, it's just when you make the accounting entry to recognize it. The "hit" you take in trading is not on the old one (which, I repeat, you've already taken), but on the NEW one. If you're going to do it, do it as soon as you can. Any reason you can't add a decent after-market cab to the TN?
I sometimes think about trading to the TN - a VERY nice tractor. In fact seriously considered one before buying what I did - the extra $7k just made me gag, hate writing checks for that kind of money. On the other hand, my little TC40 is just big enough to do serious stuff, can sneak into really tight places and is easy to tow even with the BH on it.
JEH