I don't see a change interval for the transfer case lube specified in the owner's manual. Does it need to be changed with the transmission fluid, or different interval? Also, I did the transmission a couple weeks ago and used 12 of the 14 quarts of Mercon V I bought. The manual specifies Mercon for the transfer case. Can I use the left over Mercon V or should I buy Mercon? The truck is a 2001 F150 with shift on the fly transfer case.

TIA.

 

I did exactly what you are considering doing: I used the Mercon V leftover from my tranny fluid change to fill up my T-Case.
I don't know about recommended service changes, but the fluid in my 1997 was very dirty when I drained it out at about 47,000 miles. I do engage the 4x4 quite often though.
The transfer case on my truck took about 2 quarts.
Definitely buy a $5 fluid transfer pump if you do not have one.