Well, there is a diesel shunting loco - SM03 (small loco 110kW with mechanical transistion and B wheel arrangment) but it's unnoficial.
http://eu07.pl/pliki/eu07-160704-unoff.rar - Under this adress you will find an unofficial update with SM03. You'll also need to download the physics file (SM03 in this pack has SN61 physics). The physics are here:
http://www.szwederowo.net/~starscream/Ls150.chk put this file to the .../dynamic/pkp/SM03 directory. AFAIR in this pack there is also a route with two missions created for shunting. Now a bit of theory about driving SM03 :). With the "+" and "-" you add fuel to the engine. With "/" and "*" you change gears. The positions of the gear stearing wheel are: 0-1-0-2-0-3-0-4, 0 is a positsion on which the clutch is disengaged. Remember: don't burn the clutch and that this is an unofficial version and may not work properly.
Also there is a diesel motor unit: SN61 - made in Hungary in 60s and 70s. SN61 is a DMU with mechanical transition and it's very powerfull for it's class (367kW - version with Ganz-Mavag engine). The SN61 has autoatic transition. With the main controller you change the amount of fuel that is gived to the engine. The gears change AFAIR at about 500 RPM. Well, that's all about driveable diesel locos... and DMUs in the MaSzyna simulator ;).