It is behind the ashtray, You may have to remove the ashtray mount to see it on the left in a half moon metal holder. KEZZART:

remove the entire ashtray assembly by removing the 4 easy to see hex screws, 2 at the bottom corners and two you can see at the top corners when the ash tray is opened - the cig lighter will still be attached by wires so be careful not to pull out the ash tray too hard or too far - the flasher is inside the ashtray hole to the left and may be held in place by a small clip which often comes loose so it may just be laying loose at the end of a long wire - the flasher is a squat little silver cylinder that just unplugs - remove the clip if it is still attached to the flasher and put it on the new flasher and plug in - then clip it all back in place though i just lay it loose and dont bother clipping it - i sure wonder what jerk designed it to be so hard to find and replace

The part number is 587260

22 inch

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Oldsmobile stopped making the Vista Cruiser in 1977.