Menory is fuzzy, but I think Cannonball just had a big 4x4. The first I recall seeing it was when it plowed into the lobby of the hotel or motel where the racers were grouping, followed by the unfazed driver leaning out his side window and saying "Where are the hookers?" or something like that.
One item I loved about Cannonball was that Roger Moore (who played James Bond for years) plays a guy who thinks he's James Bond...A funny touch to a funny movie.
Gumball rally came out in the 70's before monster trucks. I fondly remember that one for the Shelby 427 Cobra Peter Fonda drove. It must have been a real Shelby, as this was before Cobra replicas appeared. The scene I recall the best was when the Cobra and a Ferrari emerged from one of L.A.'s concrete canals, followed by the cobra going "WhAAAAAAaaa..." as it easily pulled away from the Ferrari as they both accelerated.
For Ferrari lovers, I remember there's a scene near the beginning where the Ferrari passes by the camera at high speed, while still in the city they start the race at...The sound of that V-12 as it passes at high RPM was like music.
I think Gumball was an attempt as a serious movie about the real life race, while Cannonball was definitely Burt Reynolds slapstick.
There was a Bigfoot in Roadhouse, as well as in Police Academy 2 & 6.
One detail about "Take This Job..." (1981) was that Bigfoot-1 was in it's early days, and did not have the giant sixty-six-inch tires yet (it was running 44 inchers, as does RF's truck I think). I recall seeing it with the forty-fours in a 4x4 magazine A year before the movie came out.
SOMETHING I JUST LEARNED: Bigfoot-2 actually got the big 66-inch meats in '82 before BF-1 got them, and as a result, #2 was probably the first true monster truck by today's standards.
I found a great site while verifying my blurring memories of Bigfoot, mentioning the history of all the Bigfoots (Bigfeet?). It mentions other movies they appeared in that I didn't include here.