hello all I have a 1990 na convertible I need to know what lubricant to use in the rear axle or how to id the axle so I can find the info.I was told if it has LSD I would need to use API GL-5 SAE 90? Is this true ? and if it does not have LSD what should I use . + what should for the man trans as well was told API service GL-4GL-5 (what) 80 w90 live in mass summer onlyfor this vert.

PS + how much for both and what brand ?I like RP
IF tou can help let me know ,and thank you so much for your helpas well as time.

help help help