ORIGINAL: pythonfan
This was posted in the hpi section and i did a little hunting and found a pic of it from hpi's own website.
http://www.rcuniverse.com/forum/m_10664116/tm.htm
And the pic of said 1/8th scale truck. You can clearly see it on the right with the spark plug wire and larger tires + body.
Looks to me as a 4.6 nitro
My guess the gasser could be 7.5cc