I now have in my possession a BBK/Walbro 190 lph pump, FRPP 3.73 gears and new rear springs (OE style but progressive). A friend of a friend is putting them in for me on Monday or Tuesday (he works for a trans shop so confidence is high). Now for the question - rear end fluid, do I use just regular 80w90 and the friction modifier, 75w90 synthetic with the friction modifier, or 85w140 synthetic with the modifier? Is it safe to use the modifier with the synthetic?

Thanks guys, I finally not have a 5.slow

 

Use synthetic, that's what I'm using in my rear end, I can't remember what weight it is though. It's safe to use friction modifier with synthetic, you're buddy should know this.

 

Yeh, I was going to double check with him next week but I am getting all the parts together.

 

Ford also makes a rear-end additive designed for their traction-loc dif.

 

Yeah, the XL3 additive. Gotta love working at a parts store....

 

synthetic 75w90 and ford friciton modifier.... any brand synthetic is good. remember the new gasket.

 

You definetly should of gotten a installation kit with those gears.

 

traction lock was rebuilt 3 years ago by previous owner (confirmed) and I will be sending all new bearings and pinion seal

 

Ohhhh OK. You might want to consider getting new axle seals and axle bearings though.

 

The guy pretty much has free reign - I will send him everything he could possibly need - I did forget the axle bearings - good looking out man. I told him to use his judgement, use whatever he suggests and send the rest back to me.