The Renault ZT3 was a tank destroyer with the same 25 mm gun in a superstructure on the hull. The development of the ZT 3 took place parallel to that of the ZT 2: a first plan in June 1935, followed by a request to Renault to produce a prototype on 12 December 1935. However, given the absence of a turret there was no need to wait for its development: Renault was instructed to quickly construct a first vehicle by adding a boiler plate superstructure to the old third AMR 35 prototype, and then sent it to Rueil where a gun could be built in and a cast commander cupola fitted.
APX indicated on 6 April 1936 — the plan to build just a single prototype already having been discarded when the second order was placed — that it desired to have five vehicles ready for the September manoeuvres of 1936. That was a very optimistic assessment, especially given the fact they themselves had not yet sent the superstructure blueprints to Renault. On 26 October Schneider announced that the five empty hulls could not be delivered before the end of April 1937 — the blueprints had not yet been received. On 27 October 1937 — the hulls at Schneider are nearing completion — APX demanded that between 15 and 20 November a "prototype" (not the original one of 1935) would be provided for acceptance. On 26 April 1938 APX approved the hull but only informed Schneider of this on 5 May.
Meanwhile between April 1936 and July 1937 Renault and the French government had had a major disagreement over the question which company should be given the order to supply the cast cupola; eventually this would be Batignolles-Châtillon. Only on 13 June 1938 Renault assembled the first vehicle (from the first series N° 95865 - 95869), that then went to Rueil to be fitted with the gun. On 9 December it was finished and Renault could begin the manufacture of the last nine vehicles (including the series M 3036 - M 3040) of the two hundred Renault ZTs: the second hull was delivered by Schneider on 31 October. The deliveries will have extended into 1939; op 2 September 1939 all GRDIs had attained their organic ZT 3 strength.
To create sufficient room with the ZT 3 the hull was raised somewhat; the roof plates on the sides and front sloped towards the apex of the vehicle where a cast rotatable copula provided the commander some height to observe his surroundings, in what was otherwise a very low and sleek construction. The gun was placed to the right of the driver with to its left a co-axial 7.5 mm machine-gun. There was an ammunition stock of eighty shells and 1200 bullets. As the position of the normal air intake was now occupied by the gun, a large roof ventilation grille was present above the third crew member, the gunner/loader. The fighting compartment was very cramped. No radio was present.
