Recently, we reported the production of the first knockout rats by combining N-ethyl-N-nitrosourea (ENU)-induced mutagenesis with a yeast-based truncation screening method. To make this new knockout technology more applicable for other laboratories and for high-throughput applications, we have developed a universal gap repair vector that is ready for use in screening for gene knockouts without additional engineering. The universal gap repair vector was validated for its application in both cDNA- and genomic DNA-based yeast truncation mutation assays. Breast cancer genes Brca1, Brca2, and Adenomatosis polyposis coli (Apc) genes from N2 rats of Brca1 and Brca2 knockouts and (Atm x ApcMin/+)F1 mice were examined, respectively. The results indicate that the universal gap repair vector we developed, using randomly selected codons as a universal cassette, is equally efficient at identifying truncation mutations as are those gap repair vectors designed specifically for Brca1 and Brca2. The availability of a universal gap repair vector should facilitate the broader screening of knockouts of most genes of many species using the combined approach of ENU-induced mutagenesis and yeast truncation assay.