How about a clay bar?!
I've used a similar product to a clay bar for road tar and it worked great. Here is a link to the stuff, expensive, but the best out there, in my opinion. Actually, this stuff works like a clay bar, but is 100 times easier. GOOD LUCK!!:thumbsup:
http://www.autopia-carcare.com/ult-3200-3322.html

make sure to wash the truck first,

tone2SS, claybar will not work on chunks of sap ,it's made to remove small particles.

Wash it real good, then try a clay bar or a little bit of reducer.:thumbsup: the big chunks should come off when you wash it. If that doesn't work try a sandblaster:rolleyes:

I've used Goo Gone, Goof Off, and kerosene with great results in the past. I've also heard WD-40 works great but I've never used it

80 grit. Sap all gone. :D

Try turtle wax bug and tar remover. I've had pretty good luck with it. WD-40 on a clean rag does wonders also.

I'll have to try to remember that next time i get some stuck on my car:unibrow:

What? It works!:D Now if you want to keep any paint on the car I do not suggest you listen to me. Ever.:_paranoid