Whats the firing order for a 5.8l engine on Ford F250?

You're likely referring to the 6.8L Triton V10 engine, as there's no 5.8L engine commonly found in Ford F250s. The firing order for the 6.8L Triton V10 is 1-5-3-6-2-10-4-8-7-9.

However, it's always best to verify this information with your specific vehicle's owner's manual or a reliable repair manual for your year and model F250. The firing order can vary slightly depending on the model year.