Here we have the 2015 Hot Wheels Off Track #79 from the HW Off-Road “Road Rally Series”.
This blue plastic bodied Baja Racer from the 2015 “A” case has a base variation. The (G31) base has a straight frame, while the (G33) frame has an X Brace. The lettering and Hot Wheels logo are different sizes and in different places.

#79 2015 Off Track X frame base

#79 2015 Off Track straight frame base

The purple pearl plastic bodied trucks (G49) from the 2015 “F” case has the same base variations.
UPDATE…..
There has been another base variation found on the Off Track, both light blue and the purple.
Here are photos thanx to our friend Dan Hammond.

Hot Wheels 2015 Off Track base Variations – light blue

Hot Wheels 2015 Off Track base Variations – purple