0000899243-03-000318 SC TO-I/A 1 20030218 QUANTA SERVICES INC 0001050915 1731 742851603 DE 1231 SC TO-I/A 34 005-54689 03569935 1360 POST OAK BLVD SUITE 2100 HOUSTON TX 77056 7133506000 1360 POST OAK BLVD SUITE 2100 HOUSTON TX 77056 QUANTA SERVICES INC 0001050915 1731 742851603 DE 1231 SC TO-I/A 1360 POST OAK BLVD SUITE 2100 HOUSTON TX 77056 7133506000 1360 POST OAK BLVD SUITE 2100 HOUSTON TX 77056 SC TO-I/A 1 dsctoia.htm AMENDMENT NO. 3