An apparatus comprising: an electric power generator; a prime mover to drive the generator, the prime mover including an equipment mount comprising a first mounting aperture and being comprised of a first material having a first thermal coefficient of expansion; a skid on which the electric power generator and prime mover are mounted, the skid comprised of a second material having a second thermal coefficient of expansion different than the first thermal coefficient of expansion, the skid including a plurality of tubular support members at least one of which defines a second mounting aperture; and a slip joint mount to connect the prime mover and the skid over a range of displacement of the prime mover relative to the skid, characterized in that: the slip joint mount includes at least one compression spring; a fastening member extends through the first mounting aperture in the equipment mount, the second mounting aperture in the tubular support member and the compression spring, at least one of the first mounting aperture and the second mounting aperture being sized to accommodate displacement between the prime mover and the skid caused by a difference between the first thermal coefficient of expansion and the second coefficient of expansion; the fastening member includes a threaded end portion that engages a retention assembly within the support member; the fastening member is secured to exert a compressive force on the compression spring to fasten the prime mover to the skid and to maintain the connection between the prime mover and the skid over the range of displacement; and the compressive force exerted on the compression spring allows a preloading to be applied to the entire slip joint mount to prevent joint slip or opening due to static and dynamic loads, while allowing the slip joint mount to slip under thermal expansion loading by overcoming the friction force of the preload applied through the compression spring. an electric power generator; a prime mover to drive the generator, the prime mover including an equipment mount comprising a first mounting aperture and being comprised of a first material having a first thermal coefficient of expansion; a skid on which the electric power generator and prime mover are mounted, the skid comprised of a second material having a second thermal coefficient of expansion different than the first thermal coefficient of expansion, the skid including a plurality of tubular support members at least one of which defines a second mounting aperture; and a slip joint mount to connect the prime mover and the skid over a range of displacement of the prime mover relative to the skid, characterized in that: the slip joint mount includes at least one compression spring; a fastening member extends through the first mounting aperture in the equipment mount, the second mounting aperture in the tubular support member and the compression spring, at least one of the first mounting aperture and the second mounting aperture being sized to accommodate displacement between the prime mover and the skid caused by a difference between the first thermal coefficient of expansion and the second coefficient of expansion; the fastening member includes a threaded end portion that engages a retention assembly within the support member; the fastening member is secured to exert a compressive force on the compression spring to fasten the prime mover to the skid and to maintain the connection between the prime mover and the skid over the range of displacement; and the compressive force exerted on the compression spring allows a preloading to be applied to the entire slip joint mount to prevent joint slip or opening due to static and dynamic loads, while allowing the slip joint mount to slip under thermal expansion loading by overcoming the friction force of the preload applied through the compression spring. the slip joint mount includes at least one compression spring; a fastening member extends through the first mounting aperture in the equipment mount, the second mounting aperture in the tubular support member and the compression spring, at least one of the first mounting aperture and the second mounting aperture being sized to accommodate displacement between the prime mover and the skid caused by a difference between the first thermal coefficient of expansion and the second coefficient of expansion; the fastening member includes a threaded end portion that engages a retention assembly within the support member; the fastening member is secured to exert a compressive force on the compression spring to fasten the prime mover to the skid and to maintain the connection between the prime mover and the skid over the range of displacement; and the compressive force exerted on the compression spring allows a preloading to be applied to the entire slip joint mount to prevent joint slip or opening due to static and dynamic loads, while allowing the slip joint mount to slip under thermal expansion loading by overcoming the friction force of the preload applied through the compression spring.