ACDelco Canister Purge Valve 214-1105 & 214-646 difference?

[XL04]

Last fall I was getting the tighten fuel cap message so I replaced that.

Then I got the check engine light with 2 codes for emissions leak. I replaced the canister vent solenoid with ACDelco 214-2149.
Then it started getting cold out and winter set in and the check engine lights stopped and tighten fuel cap message stopped. Recently it got really cold -30° and colder. My check engine light showed up again and it runs rough some times.
I figured I'd order the canister purge valve. I looked it up on Amazon under 2 different accounts and it showed 2 different part numbers. I decided to look it up on ACDelcos website and cant figure out the difference.
My vehicle is a 2004 Yukon XL 5.3 vin z and it lists both for my truck. So what's the difference?

# 214-1105
https://parts-catalog.acdelco.com/c...equest=1∂=214-1105&catalog=5560&parttype=4936

# 214-646
https://parts-catalog.acdelco.com/c...Request=1∂=214-646&catalog=5560&parttype=4936

 

[915_Tahoe]

if you give me the last 8 of vin#, i can check for you

 

[915_Tahoe]

the difference i see is that one is for flex fuel and the other is not

5.3 6.0 8.1 liter non flex
gm#12581282
ac/delco#214-1105

5.3Lw/flex 4.8L
gm#1997279
ac/delco#214-646

 

[XL04]

Thank you for the help you guys. I was thinking along the lines of one was an updated version but flex fuel would make sense.
I went ahead and order the 214-646 fingers crossed that is the problem. It all started up again when I was working on my headlight project and pulled it into a warm shop for 4 or 5 hours then brought it back outside a few times.