For my 93 L67, AC delco and Rock Auto web sites give two part number options as follows:

ACDELCO Part # AFS20 {#25162693}
SENSOR,HTD OXY(POSN 1) OEM SENSOR; IN EXH MANIFOLD/CROSSOVER-TYPE #20

ACDELCO Part # AFS21 {#25166816}
SENSOR,OXY(POSN 1) OEM SENSOR; IN EXH MANIFOLD/CROSSOVER

Since the emissions sticker on my radiator says “O2”, I presumed it is not heated and therefore bought the AFS21.
When I took existing sensor off the car, I saw it was AFS20.

Both parts are single wire.

GMPD shows part # 25162693 (AFS20) however it does not differentiate between L27 and L67 - so I’m not sure how accurate it is.
Anyone have any advice?

EDIT: Sticker says "O2S".
Is the existing one in the car the wrong part? Has anyone else with similar car used either of these Delco'*?

Non heated for the L67 that year. Single purple wire. L27 got heated (HO2S) you are not (O2S)

http://www.bonnevilleclub.com/forum/...e=article&k=16

Techinfo is your friend.

Went through the same thing on my friend'* '93 Caprice, with the exact same part numbers!

I think they're truly interchangeable, but the one that came out was an AFS20 (skinny on the top by the wire), so that'* what we went with. It'* working fine in his application. Also, check here:

www.rmsautoparts.com

I know for a fact they have plenty of both in stock! They're good people, with good prices.

The ones he'* talking about are both non-heated. I think either can be used interchangeably.