Did some math, and assuming my information is correct the 37mm SA18 should have about 37.6KJ of muzzle energy, thus also about the same amount of recoil. Which I doubt is enough to trow someone sitting in a 6.5 metric ton vehicle.
Maths for those interested: According to http://derela.pl/weap2.htm#arm the weight of the standard AP shell is half a kilogram and the muzzle velocity is 388m/s.
Thus kinetic energy should be (0.5/2)*(388^2)=37.636J
Which in turn means 37.636/4186=8,9952199KCal
Which is less energy than 3 grams of french fries. Which doesn't make sense to me but the math doesn't seem to lie. So I'm probably forgetting something very obvious or I made a rookie mistake I can't find.