Later the dual cab versions was built in Parel Loco Workshop first in 2008.

First ZDM3 class locomotive was introduced in Kalka-Shimla section of Northern Railway.

Basically a Bo-Bo design with two 2-axled bogies of 9.25t axle load with two stage suspensions. The axle bogies are of roller bearing type.

Fit for operating in 2ft 6in (762 mm) narrow-gauge sections of Indian railways with permissible axle load upto 11t.

The design incorporates necessary provisions to accomodate pony trucks at either end thus to modify the same to 1Bo-Bo1 design to reduce the axle load to 7.0t for other NG sections.

Fitted with Suri Hydro-Mechanical transmission consisting of a Trilok converter coupling to cover the road speed range from zero to 70% of max. speed & a hydro-mechanical coupling to function thereafter. Transmission to the axle drivers by means of cardan shafts.

The locos built from Parel are fitted with Voith turbo-reversible transmission having one converter for each direction of travel.

The underframe is built up of fabricated I section & plates in accordance with the conventional practice.

The cab, engine hood & radiator housing are made in different parts to facilitate removal for attention to various equipements.

Loco is fitted with compressed air brakes & vacuum brakes for the trailing stock.

For later versions (Parel make) dynamic braking by emptying the filled converter and filling opposite direction converter.

Transmission --- Suri Hydro-Mechanical transmission. Kirloskar Pnematic make Voith turbo-reversible transmission.

Axle Load --- 9.25t tonnes

Power output --- 700 hp

Bogie type --- Bo-Bo roller bearing type.

Max speed --- Varies between 25 kmph & 40 kmph.