Borgeson released a new PS box for our first gens in April 2018. Its a 12.7:1 ratio box that is a direct, bolt in replacement for the Saginaw boxes.
I had contemplated doing the IROC swap, as many have done. But it seemed like a lot of work chasing down small parts and getting the correct box. Instead, I took a chance on the new Borgeson box. It has made the Z much more enjoyable to drive. The feel is firm, the car doesn't wander as it did with the old PS unit. I feel more confident taking cloverleafs at speed.
It was an easy installation (did it when I had the engine out). Total cost was $600. $500 for the box and then $100 for the new rag joint. I reused the old PS Pump and lines, just had to flush it.
I have headers and this box clears them, as did the old Saginaw unit.
I've got about 200 miles on the new box. This is a must have if you drive your cars regularly. Thanks Borgeson!
http://www.borgeson.com/xcart/product.php?productid=1792&page=1
