188 are fine but like anything the more stress u put them under the more likely they go bang. I’ve lunched a heap of 188s in my BD but under super harsh racing conditions.
So to answer a few things as per above. I run a 210 now and it’s good. It has 6 bolt 1/2 shaft flanges cause I built it that way. The 210 with a few mods fits nicely into the 188 cradle. I have 571 Rear wheel hp and slicks so it’s under some loads.
One of the big factors is ratio. You need meat around the pinion gear. Short ratios are weaker like 3.91, 4.27 etc. 3.91 is the beginning of seeing issues. I also run diff pump and cooler and change
oil a lot to maintain longest life.
Imo the 188s are fine but once you start getting serious with HP and racing bigger is better.