SP-546 same as SP-515 plug?
 

Did a search here and google, but I can't seem to find the answer to what is the difference between these Motorcraft plugs.

Doing a plug change tomorrow and had ordered the SP-515's from Amazon, but they sent SP-546 which look the same and would fit, but I'm unsure if I should use them.

Guessing they are either a new version, or old stock. Any help is much appreciated!

What motor do you have ? Not the same plugs !

Triton 5.4

This is the 2nd change, last done 80k ago using SP-515.

Funny thing is, there are a few sites that list the plugs SP-515/SP-546.

They look identical, but there is virtually no information I can find regarding them.

what are the other numbers on the plugs
 

I see some reference to this new number but no real info

Yeah, that's what's perplexing. If I recall correctly, the original plugs before the SP-515's were different from both, and were most likely to break off in the head.

I hate to have to send these plugs back to Amazon since they were a really good price ($64 for 8), but unless I know they are indeed the same as SP-515's I'm not going to chance it.

Really aggravating on the vendors part to not have listed the plugs as some others have as SP-515/SP546. Would not have ordered them if I thought they might send something other than SP-515's.

The SP-507's broke .. replaced by the SP-515's.. never heard of the SP-546.

If it were me, I'd call the dealer with my vin and see what plugs are needed...never heard of the sp546

Just called them. They say SP-515 lol.

The secondary part# on these, PZK14F turns up as SP-515 on many searches. https://www.summitracing.com/parts/mof-sp515

The boxes look brand new. I'm beginning to think these are a newer version based on that, and so little info out on the web.

So new in fact, a google search for SP-546 turns up this thread as the second listing LMAO.

Edit: I just received this response from the vendor Auto Parts Wholesale.

The SP-515 have been superseded by the SP-546 by Ford. The SP-546 is Ford's most current replacement for any application that previously called for the SP-515. Please advise.

I'm going to be our Guinea Pig.

Maybe word was getting around that the 515's were failing out of the box. Maybe that's the replacement

I am wondering too if ford is behind this??
 

Since I am warning lots of people of out of the box failures on sp515's . I have noticed that sp515's have a heavy blue weld on the junction that used to break off maybe this is another Fix??? That kind of heat near porcelain can break it .

If it is, they need to come out with it .
Can the op post some pictures of these plugs and their boxes .