Any tips on fitting the US Car Tool Sub Frame connectors?

If the car is on a rotisserie, try this the next time around for under coating removal---Flip car over. Spray it liberally with a petroleum distillate such as PB Blaster. Let it set overnight. Turn car back to 90 degrees. Hold a garbage can near work & scrape undercoating into garbage can with a plastic paint scraper. Use a bottle of Dawn & a couple scotch-brite pads to clean the underside. Rinse & repeat (if nesc.) Sit back with a beer & admire your bottom.