Hey y'all, need a little help figuring out what parts I need for this swap. Went to O'Reilly at the end of last month to get new O2 sensors, but didn't realize I needed 2 sets. Went back today to buy the second set and they gave me the right upstream but sold me a different downstream from the one I had bought before. Bosch part # 15716 and # 15719. Looks like the difference is the 15716 has a ten inch lead and the 15719 has a 21 inch lead. Which ones do I need (or do I use both and if so which goes where?)

 

Dumb of me to not give all my truck info up front. It's a 2002 Ranger XLT 3.0L, sorry for that!