Review on 🔆 Phinlion 3600 Lumens 1156 LED Backup Bulb: Super Bright P21W BA15S 3497 7506 Bulbs for Car Truck RV Back Up Reverse Lights, 6000K Xenon White - Top Performance and Quality Assurance by Zack Frazier

I couldn't figure out why I couldn't install them at first. I tried and they just wouldn't lock (the original wasn't a problem and felt obvious). Finally, I put old and new next to each other and measured everything. There was nothing significant until I realized that the "top" (end without base) of the bulb increases in diameter MUCH faster than typical traditional bulb glass. This increase in diameter, which I call a "shoulder" enters the socket on my car wiring harness and doesn't allow the bulb to be inserted far enough for the tabs on the LED bulb to snap into the socket's latch. good looking and good feeling product. I really wanted to try them. It looks like I'll have to keep shopping now, considering the shape of that 'shoulder'. The intended application was a mid 80's GM or specifically a 1983 Oldsmobile Delta88 which Revane of course thinks this bulb should do well to replace the 1156.