Using InGaAs/AlGaAs 1060nm commercial Laser Diodes (LDs) and Laser Diode Modules (LDMs) under high current (> 2A) and nanosecond pulsed conditions offers a large flexibility for fiber Laser seeding applications. Nevertheless, the behavior and long term reliability of these LDs under such conditions is not well established. Our work focuses on determining the reliability of 1060nm seed LDs under such conditions by the extraction of Electro-Optical (EO) characteristics and the monitoring of their evolution during pulsed ageing tests. In this context, two segments of parasitic oscillations (“A” and “B” type) were observed in the optical response of LDs and LDMs driven under such conditions, with their associated threshold current (IthA and IthB) on three batches of Laser diodes, with different packaging. We observed a strong part-to-part variation in the value of IthA and a package dependency for IthB. We conducted a near-field and a time spectral analysis of the LDs optical responses. A near field widening, associated with A-type oscillations, and a temporal spectral broadening, associated with A-type and B-type oscillations, were highlighted. Step-stress ageing tests were then carried out on two batches of three LDMs each, with different values of IthA (3.9A, 7A and 11.2A for the first batch, 2.8A, 7.4A and 9.3A for the second). The modules with the lowest IthA values were the first to fail suggesting this IthA threshold as a key parameter for early failure detection. One module exhibited a gradual drop of the measured optical power. No variation of the optical power or of the IthA and IthB value were observed on the other modules, which were able to withstand the chosen ageing conditions without any noticeable decrease of their performances.