The OT-810 was a Czechoslovakian variant of the Nazi German Sd.Kfz. 251. Made by Praga and Tatra, this version had an air cooled diesel engine, and an armored roof over the troop compartment. The vehicle was not liked by those who used it and was nicknamed "Hitler's revenge".
The OT-810 is very similar in size, weight, and performance to the SdKfz 251. The biggest differences was the use of an eight cyl. Tatra air cooled diesel engine that replaced the underpowered 6 cyl. German Maybach gas engine. The hood of the OT-810 is somewhat larger to accommodate the larger engine. The Czechs also enclosed the OT-810 with hatches, partially to help protect the occupants from shrapnel and somewhat from exposure to radiation and gas.
The Czech army, desiring an army personnel carrier (the Soviets had none) utilized captured and abandoned German SdKfz 251s for their post-war armed forces. Eventually these left over vehicles wore out and a replacement
vehicle, the OT-810 was created to replace it, utilizing a similar design and constructed by Tatra and Skoda, both of whom were involved in the original construction of Wehrmacht SdKfz 251s. Approximately 2,400 OT-810s were built
and used by the Czech armed forces well into the 1980s. It is said that several hundred survive today around the globe, most being destroyed due to disarmament agreements with NATO.
While it is said that there are only about 13 operational Sdkfz 251s around the world, all in private collections, there are quite a few OT-810s in Europe and the USA, many in use by WWII reenactors.