Many of these conversion have also metal plates grafted onto the hulls to resemble a certain vehicle's silhouette - like the M109 above; the turret has been moved visually forwards, so that it resembles a Shilka. There were also Sheridans with cosmetic prothesis' on the hull (front and rear), so that they look more T-72ish; note the open front ends of the extensions, so that the driver has a better field of view:

Soviet Forces also played the disguise game - check
this artful T-34/Leopard 1 travesty:
