The ZSU-37 was a Soviet SPAAG, with only 385 being produced. It was mostly experimental, with it only being briefly used in 1945. It was later updated to the ZSU-37-2 being mass produced 1957 - 1960. It had a 6-man crew, more than the standard 4-man crew, making it more survivable. It was barely used in WW2, but since it was produced in WW2, I will include it. In WW2, the main version, (ZSU-37), was barely used in WW2, however, it was used later in the ZSU-37-2. The ZSU-37 barely saw combat, as with the ZSU-37-2, as it was very poor at dealing with fast, low-flying targets. Because of this, you will not hear much about the ZSU-37 or the ZSU-37-2. They barely saw combat, and most reports on them are biased. It was not effective even in the later version, the ZSU-57-2. The ZSU family mostly saw combat in the 6-day war.
The ZSU, being an anti-aircraft, did not have very thick armor. The armor never exceeds 15mm, and the wheels on the ZSU are exposed, making light infantry fire a threat to the ZSU's driving ability, and 7.62mm ammo can pierce through the armor with ease. Due to the thin armor it wasn't a very slow tank, and still was an ok tank in terms of its armor. The ZSU was never on the front lines due to it being an anti-aircraft, and it would sit behind the main forces.
The ZSU-37-2 had two 27mm autocannons and a state of the art radar (for the time, 1960), making it able to track enemy aircraft and be able to shoot down enemy aircraft with ease. It had a very good rate of fire, and was best used at medium flying targets. Lots of ZSU types were made, and most of them saw combat. There are still ZSU type anti-aircraft being used today.
The ZSU's flaws were mainly the thin armor it had, and infantry fire could technically go through the armor, however the chances of infantry actually coming into contact with a ZSU type was, and is, very low.
The engine used on the ZSU-37-2 was the V-105V V12 diesel engine, which was a pretty powerful one for the time. it could sustain speeds of 37 MPH on road, and 15 MPH off road. It easily cruised around obstacles, and had a pretty good engine. The transition was a pretty bad one for the time, and slightly limited the speed of the ZSU-37-2.