
343 S.E.2d 577 (1986)
Earl C. JACKSON, Jr. and Beverly Lynn Jackson
v.
HOLLOWELL CHEVROLET CO., INC., and Bobby Hollowell.
No. 851SC1324.
Court of Appeals of North Carolina.
June 3, 1986.
*578 Trimpi, Thompson & Nash by C. Everett Thompson, Elizabeth City, for plaintiffs-appellees.
Russell E. Twiford, Elizabeth City, for defendants-appellants.
WEBB, Judge.
Defendants first argue that the trial court erred in allowing plaintiffs to present evidence of the cost of replacing four tires and the battery on the Blazer. They contend that because plaintiffs did not revoke their acceptance of the truck, the measure of damages was only the difference in value of the truck with a 1980 engine with 28,000 miles and with a 1977 engine with 130,000 miles and that evidence of other expenditures was irrelevant. Assuming for the sake of argument that defendants are correct, we believe they have failed to show any resulting prejudice. The only evidence presented concerning the difference in value of the truck as represented and as actually equipped shows that the value was decreased by between $3,000 and $4,000 by installation of the 1977 engine. The jury returned a verdict awarding plaintiffs $3,000 in damages. It appears from that verdict that the jury did not consider other expenditures.
Defendants next argue that the trial court erred in admitting the testimony of Alvin Arnold, vice president of an automobile dealership, concerning the difference in value of the truck with the 1980 engine and with the 1977 engine because the witness did not have personal knowledge of the condition of the vehicle before and after the engine was installed. We disagree. It is well-established that an expert witness' testimony need not be based upon personal knowledge so long as the basis of his or her opinion is available in the record or available upon demand. Thompson v. Lenoir Transfer Company, 72 N.C.App. 348, 324 S.E.2d 619 (1985). The witness in the present case testified about the value of the truck only after listening to testimony about the difference in the engine promised and the engine actually installed. Therefore, the basis of his opinion is present in the record and his testimony was properly admitted.
Finally defendants argue that the court erred in denying their motions for directed verdict and for judgment notwithstanding the verdict because plaintiffs presented no competent evidence of their damages. Again we disagree. We have already found that Alvin Arnold's testimony about the value of the truck was properly admitted. He testified that the truck as actually equipped was worth $3,000 to $4,000 less than the truck as represented. This evidence was sufficient to allow the jury to find plaintiffs' damages. The trial court properly denied defendants' motions.
Our decision regarding defendants' assignments of error makes it unnecessary to discuss plaintiffs' cross-assignment of error regarding the dismissal of plaintiffs' claim against defendants for breach of warranty.
Affirmed.
EAGLES and PARKER, JJ., concur.
