VAN DUSEN, Circuit Judge. Defendants Baglino, Tronco and Orangio were convicted, after trial to a jury, of conspiracy and concealment of stolen goods that had been moving in interstate commerce, in contravention of 18 U.S.C. §§ 371 and 2315. The individual appeals of Tronco and Orangio, taken from the judgments of conviction entered on July 30, 1968, and of Baglino, taken from the judgment of conviction entered on August 2, 1968, were consolidated for purposes of argument and opinion.
The Government's chief witness was a co-defendant (Warren), who had entered a plea of guilty prior to trial. He testified that Baglino hired him, Tronco, Orangio and others to steal a truckload of clothing from New York City. Baglino took Warren to Morelli's Jeep Yard in Weehawken, New Jersey, to show him where the truck was to be left. Then, after further instructions, Warren went with Tronco, Orangio and one other man to New York City to steal the truck. Tronco "jumped" a parked truck, drove it a few blocks, and accompanied Warren back to Morelli's Jeep Yard, where they were met by Baglino. The trailer was parked, the tractor taken to another area, and Warren paid by Baglino. There was testimony by several law enforcement officers placing Baglino at the Morelli Yard on the night before the theft and the day after the theft. Confessions by Tronco and Orangio, confirming Warren's story and admitting participation in the unloading of the stolen clothes into a shed on the Morelli lot, were introduced after appropriate Jackson-Denno hearings on the issue of voluntariness.*fn1
Each defendant raises several procedural errors that are claimed to entitle him to reversal. We have carefully examined each contention, and find none meritorious.
The jury was selected in the presence of 10 of the 12 defendants named in the indictment. Subsequently, before trial was commenced, four defendants entered guilty pleas or had their cases severed. Baglino contends, without citation of authority, that he was, therefore, entitled to a mistrial. We find no error in the court's denial of this motion. Furthermore, the court avoided any possible prejudice by instructing the jury, on three different occasions, that they were to draw no "unfavorable inferences" from the absence of any of the co-defendants named in the indictment.*fn2
Second, Baglino contends that the failure of the court to delete from Orangio's confession, as read to the jury, a reference to "blank's home in Jersey City" prejudicially identified him to the jurors.*fn3 See Bruton v. United States, 391 U.S. 123, 88 S. Ct. 1620, 20 L. Ed. 2d 476 (1968).*fn4 We believe that the reference to Jersey City, a city with a population of some 275,000,*fn5 did not "Pose a substantial threat"*fn6 that Baglino would be identified to the jury. United States v. Lipowitz, 407 F.2d 597, 602-603 (3rd Cir. 1969); see Harrington v. California, 395 U.S. 250, 89 S. Ct. 1726, 23 L. Ed. 2d 284 (1969). In addition, the only mention of Baglino's residence to the jury came from his own testimony;*fn7 we will not allow him thus to manufacture prejudice that can subsequently be claimed as error.
Finally, Baglino claims that the summation of the Assistant United States Attorney was prejudicial. However, that summation must be taken in light of the preceding summation of Baglino's counsel. Baglino attempted to explain his presence at the Morelli lot on the night before the theft by testifying that he had been hired by the operator of that lot, John Morelli, Jr., as a night watchman. This is the story both he and Morelli had given in response to an inquiry by a policeman at that time. He further testified that his presence at the lot on the day after the theft was due to his collecting his wages. In his summation, defense counsel asked the jury why the Government had not called any witness to refute this story:
"* * * [The Government] already know that they have a witness [the policeman] * * * who is going to testify that Baglino told them, and he was confirmed by Morelli, that he was there to be a watchman. . . .
"Now, is that true or is it not true? Ladies and gentlemen of the jury, if that were not true, the United States government, with all its power, with its great FBI, with the right to call upon State Police and every other police department in the United States of America, could go out and check this thing to find out whether Mr. Baglino is telling the truth or not."
In view of this summation, the prosecutor was certainly justified in pointing out that Baglino also had the power to subpoena witnesses, including Morelli, Jr.,*fn8 to corroborate his story. E.g., United States v. Sober, 281 F.2d 244, 247 (3rd Cir. 1960).
Tronco contends that the admission of a statement by Warren that he had robbed another truck with the help of Tronco constituted reversible error.*fn9 We recognize that it is error to admit evidence of a defendant's prior criminal conduct, other than to impeach his credibility as a witness, where it is not introduced to show a common scheme. See United States v. Stirone, 262 F.2d 571, 576 (3rd Cir. 1958), rev'd. on other grounds, 361 U.S. 212, 80 S. Ct. 270, 4 L. Ed. 2d 252 (1960). Despite the clear warning of the question preceding that which evoked the challenged response, however, no objection was made to the question leading to the response. See note 9 supra. Indeed, no objection was made until the witness had been asked four more questions, and then there was only a general objection "to all of this testimony." F.R.Crim.P. 51 requires that objections be made at the time of the court's ruling and that they make "known to the court the action which [counsel] desires the court to take * * * and the grounds therefor." See, e.g., Harney v. United States, 306 F.2d 523, 525, 533-534 (1st Cir. 1962). Because the objection occurred well after the challenged testimony, it was incumbent upon counsel to make a specific request to strike; and a timely and specific objection was especially necessary in this situation to alert the court to the disagreement between two defense attorneys. The objection was neither timely nor specific, and therefore reversal is required only if "it is necessary to prevent grave miscarriages of justice." United States v. Carter, 401 F.2d 748, 750 (3rd Cir. 1968); F.R.Crim.P. 52(b). Because Warren later denied Tronco's participation and even their acquaintanceship prior to the theft involved in this case, we do not find such a necessity. To the contrary, the error was harmless. Harrington v. California, supra.
Secondly, Tronco contends that an FBI agent should not have been allowed to use a memorandum in his testimony concerning Tronco's confession. The agent testified that following his interview with Tronco he had taken his contemporaneously made notes and transcribed them into a memorandum, which was then checked for accuracy against the notes and the recollection of himself and another agent. The notes were then destroyed, pursuant to standard FBI procedure. There is no indication that the memorandum was used for any other purpose than to refresh the agent's recollection,*fn10 and this use ...