Yes, the redtop and blacktop O2 sensors use different sized bungs. If you pony up the money for the Greddy O2 housing, you will be rewarded with the correct adapter to mount your redtop sensor (and an exhaust divider, too).

The redtop replacement O2 sensor is from an 87 300zx turbo. That's Bosch #13385. You'll have to de-pin and re-pin the connector, though. No big deal.