It's a Mazda HA 3.0 diesel licensed by Perkins (same as the Perkins 4.82) Thanks everyone for your help.
Perkins
These three engines (GA/GB/GC in Perkins' internal parlance) were developed especially for Mazda and were never offered by Perkins themselves.
S2 - 2.2 L (2,209 cc) - License built Perkins 4.135 related to HA and XA, used in 1979 to 1986 Mazda Luce, Bongo/E2200, B2200, Ford Ranger
XA - 2.5 L (2,522 cc) - License built Perkins 4.154 related to HA and S2, used in 1970 Mazda E2500 and 1971 Mazda Titan, and some Bobcat skid-steer loaders. A six-cylinder version of this is called the "YA".
HA - 3.0 L (2,977 cc) - License built Perkins 4.182 related to S2 and XA
All of these engines have cast iron blocks and heads, two overhead valves per cylinder driven by maintenance-free timing gears, crossflow heads, are indirect injection. US-market B2200 and Ford Ranger trucks - and possibly the others as well - had rotary Bosch VE-style injection pumps, built by Diesel Kiki under license from Bosch.