How do you no which type of engine you have,I am ordering COP'S for my truck and this question came up.Not sure which 5.4 I have,thats my vin number below.
THANKS
VIN# 1FTRX07L9XKA38366
1999 V8-330ci 5.4L F/I Vin L
1999 V8-330ci 5.4L CNG/FI Vin M
1999 V8-330ci 5.4L BIFUEL/FI Vin Z

HEI Ignition Coil Adapter

 

you have the top one, VIN L. the second one runs on CNG (compressed natural gas) and the last one bi-fuel. the COP's are probably the same for all three applications though....