Another 3.0L discovery.......

I've thought the reinforced block was a Diamante difference, but I see your '91 block MKontero also has the lower rib. So, it appears that all of the SOHC 3.0L blocks were reinforced as a running change in '90 or '91. Here's a picture of an '89 block - note the lack of the lower horizontal rib:

[Linked Image]

Frank

'89 [color:"white"]G-Raider[color:"white"] [color:"black"]Supercharged 3.0L, MegaSquirt 2, lockup A/T, 2.5" exhaust, 172k, Cibie H4s/Oscar SCs, Hella Micro DE fogs, Cobra CB, Superwinch hubs, LSD rear/Aussie Locker front, Bilsteins, Lifeline AGM, Rust-Oleum